Interlayer for laminated glass and laminated glass

ABSTRACT

The present invention aims to provide an intermediate film for laminated glass which, in the case of being used for constituting a laminated glass, enables to improve the sound-insulating property of a laminated glass to be obtained; and a laminated glass. The intermediate film  1  for laminated glass of the present invention comprises a first layer  2  which contains a polyvinyl acetal resin and a plasticizer and the degree of acetylation of the polyvinyl acetal resin contained in the first layer  2  exceeds 30 mol %; and The laminated glass of the present invention comprises first and second components for laminated glass, and the intermediate film  1  for laminated glass sandwiched between the first and second components for laminated glass.

TECHNICAL FIELD

The present invention relates to an intermediate film for laminatedglass used for laminated glasses of automobiles and buildings. Thepresent invention specifically relates to an intermediate film forlaminated glass containing a polyvinyl acetal resin and a plasticizer,and a laminated glass comprising the intermediate film for laminatedglass.

BACKGROUND ART

Laminated glasses scatter fewer pieces of broken glass when they aredamaged by external impact, and thus are excellently safe. Therefore,such laminated glasses are widely used in automobiles, railwaycarriages, aircrafts, ships, buildings, and the like. The laminatedglass is produced by interposing an intermediate film between a pair ofglass plates.

In order to reduce the weight of a laminated glass, studies haverecently been performed for making a laminated glass thin. A thinnerlaminated glass, however, has a reduced sound-insulating property. If alaminated glass with a reduced sound-insulating property is used for thewindshield of an automobile, its sound-insulating property isdisadvantageously insufficient against sounds at a register of about5,000 Hz, such as wind noise and driving sound of wipers.

Then, additional studies have been performed for increasing thesound-insulating property of a laminated glass by changing materials ofan intermediate film.

Patent Document 1 discloses, as one example of an intermediate film forlaminated glass, a sound-insulating layer comprising 100 parts by weightof a polyvinyl acetal resin with a degree of acetalization of 60 to 85mol %, 0.001 to 1.0 parts by weight of at least one metal salt selectedfrom alkali metal salts and alkaline earth metal salts, and 30 parts byweight or more of a plasticizer. This sound-insulating layer can be usedalone as an intermediate film, or can be laminated with another layerand used as a multilayer intermediate film.

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1: JP 2007-070200 A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The intermediate film for laminated glass disclosed in the above PatentDocument 1 can improve the sound-insulating property of a laminatedglass to some extent, but a further improved sound-insulating propertyis required.

In the case of forming a laminated glass using the intermediate filmdisclosed in Patent Document 1, for example, the sound-insulatingproperty of the laminated glass in a relatively high frequency range isinsufficient, and thus reduction in the sound-insulating property due tothe coincidence effect cannot be avoided in some cases. In particular,the sound-insulating property of this laminated glass may beinsufficient at around 20° C.

Here, the coincidence effect is a phenomenon that, when sound wavesstrike a glass plate, the transverse wave is propagated on the glasssurface due to the rigidity and inertia of the glass plate, and then thetransverse wave resonates with the incident sound, so that the sound istransmitted.

Further, in the case of forming a laminated glass using a multilayerintermediate film disclosed in Patent Document 1 in which thesound-insulating layer and other layers are laminated, thesound-insulating property of the laminated glass at around 20° C. can beimproved to some extent. In this case, however, the multilayerintermediate film has the sound-insulating layer, and thus bubbleformation may occur in the laminated glass including the multilayerintermediate film.

Furthermore, recently, it has been studied to increase the amount of aplasticizer contained in an intermediate film in order to improve thesound-insulating property of a laminated glass. As the amount of aplasticizer in an intermediate film increases, the sound-insulatingproperty of the laminated glass can be improved. If the amount of aplasticizer increases, however, bubble formation may occur in thelaminated glass.

An object of the present invention is to provide an intermediate filmfor laminated glass which, if it is used for forming a laminated glass,can improve the sound-insulating property of the laminated glass to beobtained; and a laminated glass comprising the intermediate film forlaminated glass.

A limitative object of the present invention is to provide anintermediate film for laminated glass which can provide a laminatedglass that not only has a high sound-insulating property but alsosuppresses bubble formation and bubble growth; and a laminated glasscomprising the intermediate film for laminated glass.

Means for Solving the Problems

According to one wide aspect of the present invention, an intermediatefilm for laminated glass with a single layer structure or a laminatedstructure of two or more layers is provided, the intermediate filmcomprising: a first layer containing a polyvinyl acetal resin and aplasticizer, wherein a degree of acetylation of the polyvinyl acetalresin contained in the first layer exceeds 30 mol %. The intermediatefilm for laminated glass of the present invention may be a single layerintermediate film for laminated glass only comprising the first layer,or may be a multilayer intermediate film for laminated glass comprisingthe first layer.

In a certain specific aspect of the intermediate film for laminatedglass of the present invention, the intermediate film for laminatedglass has a laminated structure of two or more layers, furthercomprising a second layer disposed at the side of a first surface of thefirst layer.

In another specific aspect of the intermediate film for laminated glassof the present invention, the second layer contains a polyvinyl acetalresin, and a degree of acetylation of the polyvinyl acetal resincontained in the second layer is lower than the degree of acetylation ofthe polyvinyl acetal resin contained in the first layer.

In still another specific aspect of the intermediate film for laminatedglass of the present invention, the degree of acetylation of thepolyvinyl acetal resin contained in the second layer is 30 mol % orlower.

In another specific aspect of the intermediate film for laminated glassof the present invention, the second layer contains the polyvinyl acetalresin and a plasticizer, and an amount of the plasticizer for each 100parts by weight of the polyvinyl acetal resin in the second layer isless than an amount of the plasticizer for each 100 parts by weight ofthe polyvinyl acetal resin in the first layer.

In still another specific aspect of the intermediate film for laminatedglass of the present invention, the second layer is laminated on thefirst surface of the first layer.

In another specific aspect of the intermediate film for laminated glassof the present invention, the intermediate film for laminated glass hasa laminated structure of two or more layers, the intermediate filmfurther comprising a second layer which is laminated on a first surfaceof the first layer and which contains a polyvinyl acetal resin and aplasticizer, wherein an amount of the plasticizer is 50 parts by weightor more for each 100 parts by weight of the polyvinyl acetal resin inthe first layer, a hydroxy group content in the polyvinyl acetal resincontained in the first layer is lower than a hydroxy group content inthe polyvinyl acetal resin contained in the second layer, the differencebetween the hydroxy group content in the polyvinyl acetal resincontained in the first layer and the hydroxy group content in thepolyvinyl acetal resin contained in the second layer is 9.2 mol % orsmaller, and the degree of acetylation of the polyvinyl acetal resincontained in the first layer is 8 mol % or lower if the differencebetween the hydroxy group content in the polyvinyl acetal resincontained in the first layer and the hydroxy group content in thepolyvinyl acetal resin contained in the second layer is greater than 8.5mol % but not greater than 9.2 mol %.

In still another specific aspect of the intermediate film for laminatedglass of the present invention, the polyvinyl acetal resin contained inthe first layer contains a high-molecular-weight component with anabsolute molecular weight of 1,000,000 or higher and a proportion of thehigh-molecular-weight component in the polyvinyl acetal resin containedin the first layer is 7.4% or higher, or the polyvinyl acetal resincontained in the first layer contains a high-molecular-weight componentwith a molecular weight in terms of polystyrene of 1,000,000 or higherand a proportion of the high-molecular-weight component in the polyvinylacetal resin contained in the first layer is 9% or higher.

In another specific aspect of the intermediate film for laminated glassof the present invention, a ratio (G′(Tg+80)/G′(Tg+30)) of an elasticmodulus G′(Tg+80) at (Tg+80)° C. to an elastic modulus G′(Tg+30) at(Tg+30)° C. is 0.65 or higher, provided that the first layer is used asa resin film and a viscoelasticity of the resin film is measured, andthat Tg (° C.) represents a glass transition temperature of the resinfilm.

In still another specific aspect of the intermediate film for laminatedglass of the present invention, a ratio (G′(Tg+80)/G′(Tg+30)) of anelastic modulus G′(Tg+80) at (Tg+80)° C. to an elastic modulus G′(Tg+30)at (Tg+30)° C. is 0.65 or higher, provided that a resin film containing100 parts by weight of the polyvinyl acetal resin contained in the firstlayer and 60 parts by weight of triethylene glycol di-2-ethyl hexanoate(3GO) as a plasticizer is prepared and a viscoelasticity of the resinfilm is measured, and that Tg (° C.) represents a glass transitiontemperature of the resin film.

In another specific aspect of the intermediate film for laminated glassof the present invention, the polyvinyl acetal resin contained in thefirst layer is obtained by acetalizing a polyvinyl alcohol resin havingan average degree of polymerization exceeding 3,000.

In another specific aspect of the intermediate film for laminated glassof the present invention, the intermediate film for laminated glass hasa laminated structure of three or more layers, the intermediate filmfurther comprising: a second layer disposed at the side of a firstsurface of the first layer; and a third layer disposed at the side of asecond surface that is opposite to the first surface of the first layer.

In another specific aspect of the intermediate film for laminated glassof the present invention, the third layer contains a polyvinyl acetalresin, and a degree of acetylation of the polyvinyl acetal resincontained in the third layer is lower than a degree of acetylation ofthe polyvinyl acetal resin contained in the first layer.

In still another specific aspect of the intermediate film for laminatedglass of the present invention, the degree of acetylation of thepolyvinyl acetal resin contained in the third layer is 30 mol % orlower.

In another specific aspect of the intermediate film for laminated glassof the present invention, the third layer contains a polyvinyl acetalresin and a plasticizer, and an amount of the plasticizer for each 100parts by weight of the polyvinyl acetal resin in the third layer islower than an amount of the plasticizer for each 100 parts by weight ofthe polyvinyl acetal resin in the first layer.

In still another specific aspect of the intermediate film for laminatedglass of the present invention, the third layer is laminated on thesecond surface of the first layer.

The laminated glass of the present invention comprises a first componentfor laminated glass; a second component for laminated glass; and anintermediate film sandwiched between the first component for laminatedglass and the second component for laminated glass, wherein theintermediate film is the intermediate film for laminated glass formedaccording to the present invention.

Effect of the Invention

The intermediate film for laminated glass of the present inventioncomprises a first layer which contains a polyvinyl acetal resin and aplasticizer, and the degree of acetylation of the polyvinyl acetal resincontained in the first layer exceeds 30 mol %. Thus, thesound-insulating property of a laminated glass comprising theintermediate film for laminated glass of the present invention can beimproved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a partially cut cross-sectional view schematically showing anintermediate film for laminated glass according to one embodiment of thepresent invention.

FIG. 2 is a partially cut cross-sectional view schematically showing oneexample of a laminated glass using the intermediate film for laminatedglass shown in FIG. 1.

FIG. 3 is a diagram for illustrating the relationship between the lossfactor tan 5 and the temperature and the relationship between theelastic modulus G′ and the temperature in the case that a resin filmcontaining a polyvinyl acetal resin and triethylene glycol di-2-ethylhexanoate contained in the first layer is prepared and theviscoelasticity of the resin film is measured.

MODE(S) FOR CARRYING OUT THE INVENTION

The following will describe specific embodiments and examples of thepresent invention referring to the drawings, and thereby clarify thepresent invention.

FIG. 1 is a partially cut cross-sectional view schematically showing anintermediate film for laminated glass according to one embodiment of thepresent invention.

An intermediate film 1 shown in FIG. 1 is a multilayer intermediatefilm. The intermediate film 1 is used for obtaining a laminated glass.The intermediate film 1 is an intermediate film for laminated glass. Theintermediate film 1 comprises a first layer 2, a second layer 3 disposedon the side of a first surface 2 a of the first layer 2, and a thirdlayer 4 disposed on the side of a second surface 2 b opposite to thefirst surface 2 a of the first layer 2. The second layer 3 is laminatedon the first surface 2 a of the first layer 2. The third layer 4 islaminated on the second surface 2 b of the first layer 2. The firstlayer 2 is an intermediate layer, and mainly functions as asound-insulating layer. The second layer 3 and the third layer 4 areprotecting layers, and are surface layers in the present embodiment. Thefirst layer 2 is disposed between the second layer 3 and the third layer4. The first layer 2 is sandwiched between the second layer 3 and thethird layer 4. Thus, the intermediate film 1 has a multilayer structurein which the second layer 3, the first layer 2, and the third layer 4are laminated in this order.

In addition, other layers may be laminated between the first layer 2 andthe second layer 3 and between the first layer 2 and the third layer 4.Preferably, the first layer 2 and the second layer 3, and the firstlayer 2 and the third layer 4 each are laminated directly. Examples ofother layers include layers containing a thermoplastic resin such aspolyvinyl acetal resin, and layers containing polyethyleneterephthalate.

The first layer 2 contains a polyvinyl acetal resin with a degree ofacetylation exceeding 30 mol % and a plasticizer. The second layer 3preferably contains a polyvinyl acetal resin, and preferably contains apolyvinyl acetal resin and a plasticizer. The second layer 3 contains,for example, a polyvinyl acetal resin with a degree of acetylation of 30mol % or lower and a plasticizer. The third layer 4 preferably containsa polyvinyl acetal resin, and preferably contains a polyvinyl acetalresin and a plasticizer. The third layer 4 contains, for example, apolyvinyl acetal resin with a degree of acetylation of 30 mol % or lowerand a plasticizer. The composition of the first layer 2 and thecompositions of the second layer 3 and the third layer 4 are preferablydifferent from each other. The compositions of the second layer 3 andthe third layer 4 may be the same as or different from each other.

The main features of the present embodiment are that the first layer 2containing a polyvinyl acetal resin and a plasticizer is comprised and adegree of acetylation of the polyvinyl acetal resin contained in thefirst layer 2 has a degree of acetylation exceeds 30 mol %. Inparticular, the present embodiment has an important feature in that thedegree of acetylation of the polyvinyl acetal resin contained in thefirst layer 2 is as high as exceeding 30 mol %. Thereby, thesound-insulating property of a laminated glass comprising theintermediate film 1 can be improved.

Especially, the first layer 2 containing a polyvinyl acetal resin with adegree of acetylation exceeding 30 mol % can improve thesound-insulating property within a temperature range of 20° C. to 30° C.

In recent years, fuel automobiles using internal-combustion engines arebeing switched over to electric vehicles using electric motors, andhybrid electric vehicles using internal-combustion engines and electricmotors, and the like. Laminated glasses used for fuel automobiles usinginternal-combustion engines are particularly required to have asound-insulating property against sounds in a relatively low frequencyrange. Even laminated glasses used for fuel automobiles usinginternal-combustion engines also preferably have a high sound-insulatingproperty against sounds in a high frequency range. In contrast,laminated glasses used for electric vehicles and hybrid electricvehicles utilizing electric motors are particularly required to have ahigh sound-insulating property against sounds in a high frequency rangein order to effectively insulate driving sounds of their electricmotors.

The present inventors have also found that the first layer 2 containinga polyvinyl acetal resin with a degree of acetylation exceeding 30 mol %can effectively and sufficiently improve the sound-insulating propertyin a high frequency range of a laminated glass.

In the intermediate film 1, the second layer 3 and the third layer 4 arelaminated on the respective faces of the first layer 2. The second layeris preferably disposed on the side of a first surface of the firstlayer, and the second layer is preferably laminated on the first surfaceof the first layer. The second layer may be disposed only on the side ofthe first surface of the first layer, and the third layer may not bedisposed on the side of a second surface of the first layer.Nevertheless, it is preferable that the second layer is disposed on theside of the first surface of the first layer and the third layer isdisposed on the second surface of the first layer. The third layer ispreferably laminated on the second surface of the first layer. As thethird layer is laminated on the second surface of the first layer, thepenetration resistance of a laminated glass comprising the intermediatefilm 1 can be further improved.

With an intermediate film for laminated glass having a multilayerstructure that provides an improved sound-insulating property, bubbleformation problematically easily occurs in the laminated glass. Withrespect to such a problem, the present inventors have found that, in anintermediate film for laminated glass with a multilayer structure,plasticizers transfer between the respective layers and, as a result, alayer containing a larger amount of plasticizer is formed, that is, forexample, the plasticizers transfer from the second layer and the thirdlayer to the first layer so that the amount of the plasticizer in thefirst layer increases. The present inventors have further found that, asthe layer containing a larger amount of plasticizer is formed, in otherwords, as the amount of the plasticizer in the first layer increases,bubble formation is likely to occur in a laminated glass comprising theintermediate film for laminated glass, and bubble formation once occurs,the generated bubbles tend to serve as cores and thereby to cause bubblegrowth.

From the viewpoint of suppressing bubble formation and bubble growth ina laminated glass, preferably, the amount of the plasticizer is 50 partsby weight or more for each 100 parts by weight of the polyvinyl acetalresin in the first layer 2; the hydroxy group content in the polyvinylacetal resin contained in the first layer 2 is lower than the hydroxygroup content in the polyvinyl acetal resin contained in the secondlayer 3; the difference between the hydroxy group content in thepolyvinyl acetal resin contained in the first layer 2 and the hydroxygroup content in the polyvinyl acetal resin contained in the secondlayer 3 (hereinafter, also referred to as a content difference (1-2)) is9.2 mol % or smaller; and if the difference between the hydroxy groupcontent in the polyvinyl acetal resin contained in the first layer 2 andthe hydroxy group content in the polyvinyl acetal resin contained in thesecond layer 3 (content difference (1-2)) is greater than 8.5 mol % butnot greater than 9.2 mol %, the degree of acetylation of the polyvinylacetal resin contained in the first layer 2 is preferably 8 mol % orlower. The content difference (1-2) may be greater than 8.5 mol % butnot greater than 9.2 mol %, and further may be 8.5 mol % or smaller.

Preferably, the hydroxy group content in the polyvinyl acetal resincontained in the first layer 2 is lower than the hydroxy group contentin the polyvinyl acetal resin contained in the third layer 4; thedifference between the hydroxy group content in the polyvinyl acetalresin contained in the first layer 2 and the hydroxy group content inthe polyvinyl acetal resin contained in the third layer 4 (hereinafter,also referred to as a content difference (1-3)) is 9.2 mol % or smaller;and if the difference between the hydroxy group content in the polyvinylacetal resin contained in the first layer 2 and the hydroxy groupcontent in the polyvinyl acetal resin contained in the third layer 4(content difference (1-3)) is greater than 8.5 mol % but not greaterthan 9.2 mol %, the degree of acetylation of the polyvinyl acetal resincontained in the first layer 2 is 8 mol % or lower. Even in the casethat the content difference (1-3) is 8.5 mol % or smaller, however, thedegree of acetylation of the polyvinyl acetal resin contained in thefirst layer 2 is preferably 8 mol % or lower if the content difference(1-2) is greater than 8.5 mol % but not greater than 9.2 mol %. Thecontent difference (1-3) may be greater than 8.5 mol % but not greaterthan 9.2 mol % or lower, and further may be 8.5 mol % or smaller.

The present inventors have performed studies for suppressing bubbleformation and bubble growth, and thereby found that the aforementionedcontrol of the hydroxy group contents in the polyvinyl acetal resinscontained in the first layer, the second layer and the third layerenables to sufficiently suppress bubble formation and bubble growth in alaminated glass. Since transition of the plasticizer can be suppressedand bubble formation and bubble growth in a laminated glass can besufficiently suppressed, the amount of the plasticizer in each layer,especially the amount of the plasticizer in the first layer 2, can beincreased. As a result, the sound-insulating property of the laminatedglass can be furthermore improved.

If the amount of the plasticizer for each 100 parts by weight of thepolyvinyl acetal resin in the first layer 2 is more than the amount ofthe plasticizer for each 100 parts by weight of the polyvinyl acetalresin in each of the second layer 3 and the third layer 4, bubbleformation tends to more easily occur. In addition, bubble formation onceoccurs, the generated bubbles tend to serve as cores and thereby tocause bubble growth. In contrast, if the hydroxy group contents in thepolyvinyl acetal resins contained in the first layer, the second layerand the third layer are controlled as mentioned above, bubble formationand bubble growth in a laminated glass can be sufficiently suppressed.

From the viewpoint of further suppressing bubble formation and bubblegrowth in a laminated glass, with respect to the difference between thehydroxy group content in the polyvinyl acetal resin contained in thefirst layer 2 and each of the hydroxy group contents in the polyvinylacetal resins contained in the second layer 3 and the third layer 4(content difference (1-2) and content difference (1-3)), the lower limitthereof is preferably 0.1 mol %, more preferably 1 mol %, and still morepreferably 2 mol %, whereas the upper limit thereof is preferably 8.5mol %, more preferably 7.8 mol %, still more preferably 7 mol %, andparticularly preferably 5.6 mol %. Because bubble formation and bubblegrowth can be furthermore suppressed in a laminated glass, thedifference between the hydroxy group content in the polyvinyl acetalresin contained in the first layer 2 and each of the hydroxy groupcontents in the polyvinyl acetal resins contained in the second layer 3and the third layer 4 (content difference (1-2) and content difference(1-3)) is preferably 5 mol % or smaller, more preferably 4.5 mol % orsmaller, still more preferably 4 mol % or smaller, and furthermorepreferably 3.5 mol % or smaller.

Preferably, the polyvinyl acetal resin contained in the first layer 2contains a high-molecular-weight component with an absolute molecularweight of 1,000,000 or higher (hereinafter, also referred to as ahigh-molecular-weight component X), or the polyvinyl acetal resincontained in the first layer 2 contains a high-molecular-weightcomponent with a polystyrene-equivalent molecular weight (hereinafter,also referred to as a molecular weight y) of 1,000,000 or higher(hereinafter, also referred to as a high-molecular-weight component Y).The high-molecular-weight component X and the high-molecular-weightcomponent Y are polyvinyl acetal resins. The proportion of thehigh-molecular-weight component X in the polyvinyl acetal resincontained in the first layer 2 is preferably 7.4% or higher, or theproportion of the high-molecular-weight component Y in the polyvinylacetal resin contained in the first layer 2 is preferably 9% or higher.

As the polyvinyl acetal resin contained in the first layer 2 containsthe high-molecular-weight component X with an absolute molecular weightof 1,000,000 or higher at the aforementioned specific proportion, bubbleformation in a laminated glass can be suppressed. As the polyvinylacetal resin contained in the first layer 2 contains thehigh-molecular-weight component Y with a molecular weight y of 1,000,000or higher at the aforementioned specific proportion, bubble formation ina laminated glass can also be suppressed.

The proportion of the high-molecular-weight component X in the polyvinylacetal resin contained in the first layer 2 is defined as a value interms of percentage (%) of the ratio of the area of a regioncorresponding to the high-molecular-weight component X in the peak areaof the polyvinyl acetal resin component obtained upon measuring theabsolute molecular weight. Also, the proportion of thehigh-molecular-weight component Y in the polyvinyl acetal resincontained in the first layer 2 is defined as a value in terms ofpercentage (%) of the ratio of the area of a region corresponding to thehigh-molecular-weight component Y in the peak area of the polyvinylacetal resin component obtained upon measuring the molecular weight interms of polystyrene.

The compositions of the second layer 3 and the third layer 4 each arepreferably different from the composition of the first layer 2. Thepolyvinyl acetal resin in each of the second layer 3 and the third layer4 may contain a high-molecular-weight component X with an absolutemolecular weight of 1,000,000 or higher and the proportion of thehigh-molecular-weight component X in the polyvinyl acetal resincontained in each of the second layer 3 and the third layer 4 may be7.4% or higher. It may also contain a high-molecular-weight component Ywith a molecular weight y of 1,000,000 or higher and the proportion ofthe high-molecular-weight component Y in the polyvinyl acetal resincontained in each of the second layer 3 and the third layer 4 may be 9%or higher.

From the viewpoints of further improving the sound-insulating propertyof a laminated glass and further suppressing bubble formation and bubblegrowth, with respect to the proportion of the high-molecular-weightcomponent X with an absolute molecular weight of 1,000,000 or higher inthe polyvinyl acetal resin contained in the first layer 2, a preferablelower limit is 8%, a more preferable lower limit is 8.5%, a still morepreferable lower limit is 9%, a particularly preferable lower limit is9.5%, and a most preferable lower limit is 10%. Because thesound-insulating property of a laminated glass can be further improvedand bubble formation and bubble growth can be further suppressed, theproportion of the high-molecular-weight component X is preferably 11% orhigher, more preferably 12% or higher, still more preferably 14% orhigher, and particularly preferably 16% or higher. The upper limit ofthe proportion of the high-molecular-weight component X is notparticularly limited, and a preferable upper limit is 40%, a morepreferable upper limit is 30%, and a still more preferable upper limitis 25%.

In the case that the polyvinyl acetal resin contained in the first layer2 contains the high-molecular-weight component Y with a molecular weighty of 1,000,000 or higher, with respect to the proportion of thehigh-molecular-weight component Y with a molecular weight y of 1,000,000or higher in the polyvinyl acetal resin contained in the first layer 2containing the high-molecular-weight component Y, a preferable lowerlimit is 10%, a more preferable lower limit is 11%, a still morepreferable lower limit is 11.5%, and a particularly preferable lowerlimit is 12%. Because the sound-insulating property of a laminated glasscan be further improved and bubble formation and bubble growth can befurther improved, the proportion of the high-molecular-weight componentY is preferably 12.5% or higher, more preferably 13.5% or higher, stillmore preferably 14% or higher, particularly preferably 15% or higher,and most preferably 18% or higher. The upper limit of the proportion ofthe high-molecular-weight component Y is not particularly limited, and apreferable upper limit is 40%, a more preferable upper limit is 30%, anda still more preferable upper limit is 25%. If the proportion of thehigh-molecular-weight component Y is not lower than the lower limit, thesound-insulating property of a laminated glass can be further improvedand bubble formation and bubble growth can be further suppressed.

In the case that a resin film A containing 100 parts by weight of thepolyvinyl acetal resin contained in the first layer 2 and 60 parts byweight of triethylene glycol di-2-ethyl hexanoate (3GO) as a plasticizeris used and the viscoelasticity of the resin film A is measured (testmethod A), the ratio (G′(Tg+80)/G′(Tg+30)) of the elastic modulusG′(Tg+80) at (Tg+80)° C. to the elastic modulus G′(Tg+30) at (Tg+30)° C.is preferably 0.65 or higher, provided that Tg(° C.) represents a glasstransition temperature of the resin film A.

Also, in the case that the first layer 2 is used as a resin film B andthe viscoelasticity of the resin film B is measured (test method B), theratio (G′(Tg+80)/G′(Tg+30)) of the elastic modulus G′(Tg+80) at (Tg+80)°C. to the elastic modulus G′(Tg+30) at (Tg+30)° C. is preferably 0.65 orhigher, provided that Tg(° C.) represents the glass transitiontemperature of the resin film B.

In the test method B, the first layer 2 is used as the resin film B, andthe first layer 2 itself is the resin film B.

The resin film B is the first layer 2, and it contains the polyvinylacetal resin and the plasticizer at the weight ratio as in the firstlayer 2. In the test method B, preferably, the plasticizer istransferred in the intermediate film 1 for laminated glass, and then theelastic modulus G′(Tg+80) and the elastic modulus G′(Tg+30) aremeasured. In the test method B, more preferably, the intermediate film 1for laminated glass is stored at a humidity of 30% (±3%) and at atemperature of 23° C. for one month so that the plasticizer istransferred in the intermediate film 1 for laminated glass, and then theelastic modulus G′(Tg+80) and the elastic modulus G′(Tg+30) aremeasured.

The present inventors have performed studies for suppressing bubbleformation and bubble growth, and thereby also found that a ratio(G′(Tg+80)/G′(Tg+30)) of 0.65 or higher in the test method A or the testmethod B enables to sufficiently suppress bubble formation and bubblegrowth in a laminated glass. Even in the case that the amount of theplasticizer in the first layer 2 is large, bubble formation and bubblegrowth in a laminated glass can be sufficiently suppressed. Thus, thesound-insulating property of the laminated glass can be improved. Inparticular, use of an intermediate film 1 for laminated glass in whichthe second layer 3 and the third layer 4 are laminated on the respectivesurfaces of the first layer 2 configured to have a ratio(G′(Tg+80)/G′(Tg+30)) of 0.65 or higher leads to further suppression ofbubble formation and bubble growth in a laminated glass.

The ratio (G′(Tg+80)/G′(Tg+30)) is 0.65 or higher, and preferably 1.0 orlower. A ratio (G′(Tg+80)/G′(Tg+30)) of 0.65 or higher may enable tosufficiently suppress bubble formation and bubble growth in a laminatedglass even after the laminated glass is stored under considerably severeconditions or for a long term. Further, a ratio (G′(Tg+80)/G′(Tg+30))not lower than the lower limit and not higher than the upper limit mayenable to more effectively suppress bubble formation and bubble growthin a laminated glass even after the laminated glass is stored underconsiderably severe conditions or for a long term.

From the viewpoint of sufficiently improving the sound-insulatingproperty of a laminated glass, the amount of the plasticizer ispreferably 40 parts by weight or more for each 100 parts by weight ofthe polyvinyl acetal resin in the first layer 2. Even in the case thatthe amount of the plasticizer in the first layer is large, the firstlayer configured to have a ratio (G′(Tg+80)/G′(Tg+30)) of 0.65 or highermay enable to suppress bubble formation and bubble growth in a laminatedglass.

The glass transition temperature Tg(° C.) indicates a peak temperatureof the loss factor tan δ obtainable from the measurement result of theviscoelasticity. From the viewpoint of further suppressing bubbleformation and bubble growth in a laminated glass, the ratio(G′(Tg+80)/G′(Tg+30)) is more preferably 0.7 or higher, whereas morepreferably 0.95 or lower, and still more preferably 0.75 or higher,whereas still more preferably 0.9 or lower. Particularly, in the case ofcontrolling the ratio (G′(Tg+80)/G′(Tg+30)) by the average degree ofpolymerization of polyvinyl alcohol resin, the ratio(G′(Tg+80)/G′(Tg+30)) is preferably 0.65 or higher, more preferably 0.66or higher, still more preferably 0.67 or higher, and particularlypreferably 0.7 or higher, whereas preferably 0.82 or lower, and morepreferably 0.8 or lower, because bubble formation and bubble growth in alaminated glass can be sufficiently suppressed and the sound-insulatingproperty of the laminated glass can be further improved. Furthermore, ifthe ratio (G′(Tg+80)/G′(Tg+30)) is 0.82 or lower, or 0.8 or lower, anintermediate film can be easily formed.

Examples of the method for controlling the ratio (G′(Tg+80)/G′(Tg+30))measured by the test method A or the test method B to 0.65 or higherinclude a method of using a polyvinyl alcohol resin with a relativelyhigh average degree of polymerization upon synthesis of a polyvinylacetal resin to be contained in the first layer 2; and a method ofstrengthening the inter-molecular interaction of the polyvinyl acetalresin contained in the first layer 2. Examples of the method ofstrengthening the inter-molecular interaction of the polyvinyl acetalresin contained in the first layer 2 include a method of physicallycross-linking the molecules of the polyvinyl acetal resin, and a methodof chemically cross-linking the molecules. Particularly preferable are amethod of using a polyvinyl alcohol resin with a relatively high averagedegree of polymerization upon synthesis of a polyvinyl acetal resin tobe contained in the first layer 2 and a method of physicallycross-linking the molecules of the polyvinyl acetal resin contained inthe first layer 2 because the intermediate film 1 can be easily formedusing an extruder.

The following will describe one example of the relationship between theloss factor tan δ and the temperature and the relationship between theelastic modulus G′ and the temperature obtained by the aforementionedmeasurement of the viscoelasticity referring to FIG. 3.

The loss factor tan δ and the temperature show the relationship shown inFIG. 3. The temperature at the peak P of the loss factor tan δ is theglass transition temperature Tg.

In FIG. 3, the glass transition temperature Tg in the elastic modulus G′drawn with the broken line A2 and the glass transition temperature Tg inthe elastic modulus G′ drawn with the solid line A1 are the sametemperature. For example, as the amount of change D of the elasticmodulus G′(Tg+80) based on the elastic modulus G′(Tg+30) is smaller,bubble formation and bubble growth in a laminated glass can be moreeffectively suppressed. The amount of change D1 in the elastic modulusG′ drawn with the solid line A1 is smaller than the amount of change D2in the elastic modulus G′ drawn with the broken line A2. Thus, in FIG.3, bubble formation and bubble growth in a laminated glass can be moreeffectively suppressed in the case of the elastic modulus G′ drawn withthe solid line A1 in which the amount of change D1 is relatively smallthan in the case of the elastic modulus G′ drawn with the broken line A2in which the amount of change D2 is relatively large.

The elastic modulus G′(Tg+30) is preferably 200,000 Pa or higher. Theelastic modulus G′(Tg+30) is more preferably 220,000 Pa or higher, stillmore preferably 230,000 Pa or higher, and particularly preferably240,000 Pa or higher, whereas preferably 10,000,000 Pa or lower, morepreferably 5,000,000 Pa or lower, particularly preferably 1,000,000 Paor lower, most preferably 500,000 Pa or lower, and still most preferably300,000 Pa or lower. An elastic modulus G′(Tg+30) not lower than thelower limit may enable to further suppress bubble formation and bubblegrowth in a laminated glass.

Here, the relationship between the elastic modulus G′ and thetemperature is greatly influenced by the type of a polyvinyl acetalresin and, in particular, it is greatly influenced by the average degreeof polymerization of the polyvinyl alcohol resin used for providing apolyvinyl acetal resin. The relationship is not greatly influenced bythe type of a plasticizer and, if the plasticizer is used in a usualamount of plasticizer, the amount of the plasticizer does not have agreat influence thereon. In the case of using a plasticizer such as amonobasic organic acid ester other than 3GO instead of 3GO, especiallyin the case of using a diester plasticizer represented by the followingformula (1) other than 3GO, or using triethylene glycol di-2-ethylbutyrate (3 GH) and triethylene glycol di-n-heptanoate (3G7), the ratio(G′(Tg+80)/G′(Tg+30)) is not greatly different from the ratio(G′(Tg+80)/G′(Tg+30)) in the case of using 3GO. Further, in the casethat the amount of the plasticizer is 50 to 80 parts by weight for each100 parts by weight of the polyvinyl acetal resin, the ratios(G′(Tg+80)/G′(Tg+30)) are not greatly different from each other. Theratio (G′(Tg+80)/G′(Tg+30)) measured using a resin film containing 100parts by weight of a polyvinyl acetal resin and 60 parts by weight oftriethylene glycol di-2-ethyl hexanoate (3GO) as a plasticizer is notgreatly different from the ratio (G′(Tg+80)/G′(Tg+30)) measured usingthe first layer 2 itself. The ratios (G′(Tg+80)/G′(Tg+30)) obtained bythe test method A and the test method B each are preferably 0.65 orhigher, and it is more preferable that the ratio (G′(Tg+80)/G′(Tg+30))obtained by the test method B is 0.65 or higher.

Also, in order to suppress bubble formation in the intermediate film forlaminated glass, the polyvinyl acetal resin contained in the first layer2 is preferably obtained by acetalization of a polyvinyl alcohol resinwith an average degree of polymerization exceeding 3,000. In this case,the ratio (G′(Tg+80)/G′(Tg+30)) is not necessarily 0.65 or higher, butis preferably 0.65 or higher. From the viewpoint of further suppressingbubble formation and bubble growth in a laminated glass, the amount ofthe plasticizer is preferably 40 parts by weight or more for each 100parts by weight of the polyvinyl acetal resin obtained by acetalizing apolyvinyl alcohol resin with an average degree of polymerizationexceeding 3,000 in the first layer 2. In addition, from the viewpoint offurther suppressing bubble formation and bubble growth in a laminatedglass, the hydroxy group content is preferably 30 mol % or lower in thepolyvinyl acetal resin obtained by acetalizing a polyvinyl alcohol resinwith an average degree of polymerization exceeding 3,000 in the firstlayer 2.

From the viewpoint of further improving the sound-insulating property ofa laminated glass, the amount of the plasticizer is preferably 40 partsby weight or more, more preferably 50 parts by weight or more, stillmore preferably 55 parts by weight or more, and particularly preferably60 parts by weight or more, for each 100 parts by weight of thepolyvinyl acetal resin in the first layer 2. Even in the case that theamount of the plasticizer is large in the first layer 2 as mentionedabove, bubble formation and bubble growth in a laminated glass can bemore effectively suppressed by controlling the hydroxy group contents inthe polyvinyl acetal resins contained in the first layer, the secondlayer and the third layer as mentioned above, by controlling theproportion of the high-molecular-weight component X with an absolutemolecular weight of 1,000,000 or higher or the proportion of thehigh-molecular-weight component Y with a molecular weight y of 1,000,000or higher, or by controlling the ratio (G′(Tg+80)/G′(Tg+30)).

The following will describe the details of the first layer, the secondlayer and the third layer forming the intermediate film for laminatedglass of the present invention and the details of the polyvinyl acetalresins and the plasticizers contained in the first layer, the secondlayer and the third layer.

(Thermoplastic Resin)

The polyvinyl acetal resin contained in the first layer (hereinafter,also referred to as a polyvinyl acetal resin (1)) is not particularlylimited as long as the degree of acetylation (acetyl group amount)exceeds 30 mol %. The second layer preferably contains a thermoplasticresin, and more preferably contains a polyvinyl acetal resin(hereinafter, also referred to as a polyvinyl acetal resin (2)). Thethird layer preferably contains a thermoplastic resin, and morepreferably contains a polyvinyl acetal resin (hereinafter, also referredto as a polyvinyl acetal resin (3)). If the thermoplastic resinscontained in the second layer and the third layer are the polyvinylacetal resin (2) and the polyvinyl acetal resin (3), the adhesive forcesbetween the second layer and the third layer and the respectivecomponents of laminated glass become sufficiently high.

Examples of the thermoplastic resin include polyvinyl acetal resin,ethylene/vinyl acetate copolymerized resin, ethylene/acryl copolymerizedresin, polyurethane resin, and polyvinyl alcohol resin. Thermoplasticresins other than these may be used.

The degree of acetylation of the polyvinyl acetal resin (1) exceeds 30mol %. A preferable lower limit thereof is 30.5 mol %, a more preferablelower limit is 32 mol %, a still more preferable lower limit is 35 mol%, and a particularly preferable lower limit is 40 mol %, whereas apreferable upper limit is 90 mol %, a still more preferable upper limitis 80 mol %, a particularly preferable upper limit is 70 mol %, and amost preferable upper limit is 50 mol %. If the degree of acetylation isnot lower than the lower limit, the sound-insulating property of anintermediate film and a laminated glass is high. As the degree ofacetylation is not lower than the lower limit, the compatibility betweenthe polyvinyl acetal resin (1) and the plasticizer may be high.

The degree of acetylation of each of the polyvinyl acetal resin (2) andthe polyvinyl acetal resin (3) is preferably lower than the degree ofacetylation of the polyvinyl acetal resin (1). As the degree ofacetylation of each of the polyvinyl acetal resin (2) and the polyvinylacetal resin (3) is lower than the degree of acetylation of thepolyvinyl acetal resin (1), the penetration resistance of a laminatedglass can be further improved.

The degree of acetylation of each of the polyvinyl acetal resin (2) andthe polyvinyl acetal resin (3) is preferably 0 mol % or higher, morepreferably 0.1 mol % or higher, and still more preferably 0.5 mol % orhigher, whereas preferably 30 mol % or lower, more preferably 20 mol %or lower, still more preferably 10 mol % or lower, particularlypreferably 5 mol % or lower, and most preferably 3 mol % or lower. Ifthe degree of acetylation is not higher than the upper limit, thepenetration resistance of an intermediate film and a laminated glass maybe high. Further, if the degree of acetylation is not higher than theupper limit, bleed out of the plasticizer can be suppressed.

If the degree of acetylation of each of the polyvinyl acetal resin (2)and the polyvinyl acetal resin (3) is 3 mol % or lower, the mechanicalproperties of an intermediate film may be further improved. As a result,the penetration resistance of a laminated glass can be further improved.

The degree of acetylation is a value of mole fraction in terms ofpercentage (mol %) obtained by subtracting the amount of ethylene groupsbonded with acetal groups and the amount of ethylene groups bonded withhydroxy groups from the total amount of ethylene groups in the mainchain, and then dividing this value by the total amount of ethylenegroups in the main chain. The amount of ethylene groups bonded withacetal groups can be measured in conformity with JIS K6728 “TestingMethods for Polyvinyl Butyral”, for example.

The difference between the degree of acetylation of the polyvinyl acetalresin (1) and the degree of acetylation of the polyvinyl acetal resin(2), and the difference between the degree of acetylation of thepolyvinyl acetal resin (1) and the degree of acetylation of thepolyvinyl acetal resin (3) each are preferably 10 mol % or higher, andmore preferably 20 mol % or higher, whereas preferably 50 mol % orlower, and more preferably 30 mol % or lower. If the difference betweenthe degree of acetylation of the polyvinyl acetal resin (1) and that ofeach of the polyvinyl acetal resin (2) and the polyvinyl acetal resin(3) is not lower than the lower limit and not higher than the upperlimit, the sound-insulating property and the penetration resistance ofan intermediate film and a laminated glass can be further improved.

The polyvinyl acetal resin (1), polyvinyl acetal resin (2) and thepolyvinyl acetal resin (3) can be produced by, for example, acetalizingpolyvinyl alcohol with an aldehyde. The polyvinyl alcohol can beobtained by, for example, saponifying polyvinyl acetate. The degree ofsaponification of the polyvinyl alcohol is generally within a range of70 to 99.9 mol %, and it is preferably within a range of 75 to 99.8 mol%, and more preferably 80 to 99.8 mol %.

The average degree of polymerization of the polyvinyl alcohol forobtaining each of the polyvinyl acetal resin (1), polyvinyl acetal resin(2) and the polyvinyl acetal resin (3) is preferably 200 or higher, morepreferably 500 or higher, still more preferably 1,600 or higher,particularly preferably 2,600 or higher, and most preferably 2,700 orhigher, whereas preferably 5,000 or lower, more preferably 4,000 orlower, and still more preferably 3,500 or lower. If the average degreeof polymerization is not lower than the lower limit, the penetrationresistance of a laminated glass can be further improved. If the averagedegree of polymerization is not higher than the upper limit, anintermediate film can be easily formed.

From the viewpoint of further improving the penetration resistance of alaminated glass, the average degree of polymerization of the polyvinylalcohol is particularly preferably 2,700 or higher and 5,000 or lower.

From the viewpoint of further suppressing bubble formation and bubblegrowth in a laminated glass, with respect to the average degree ofpolymerization of the polyvinyl alcohol resin for obtaining thepolyvinyl acetal resin (1) contained in the first layer, a preferablelower limit is 3,010, a preferable lower limit is 3,050, a preferablelower limit is 3,500, a preferable lower limit is 3,600, a preferablelower limit is 4,000, and a preferable lower limit is 4,050, whereas apreferable upper limit is 7,000, a preferable upper limit is 6,000, apreferable upper limit is 5,000, a preferable upper limit is 4,900, anda preferable upper limit is 4,500. In particular, because bubbleformation and bubble growth in a laminated glass can be furthersuppressed, the sound-insulating property of a laminated glass can besufficiently improved, and an intermediate film can be easily formed,the average degree of polymerization of the polyvinyl alcohol resin forobtaining the polyvinyl acetal resin (1) contained in the first layer ispreferably 3,010 or higher, and more preferably 3,020 or higher, whereaspreferably 4,000 or lower, more preferably lower than 4,000, still morepreferably 3,800 or lower, particularly preferably 3,600 or lower, andmost preferably 3,500 or lower.

The polyvinyl acetal resin (2) and the polyvinyl acetal resin (3)contained in the second layer and the third layer, respectively, can beproduced by acetalizing a polyvinyl alcohol resin. With respect to theaverage degree of polymerization of the polyvinyl alcohol resin forobtaining the polyvinyl acetal resin (2) and the polyvinyl acetal resin(3) contained in the second layer and the third layer, a preferablelower limit is 200, a more preferable lower limit is 500, a still morepreferable lower limit is 1,000, and a particularly preferable lowerlimit is 1,500, whereas a preferable upper limit is 4,000, a morepreferable upper limit is 3,500, a still more preferable upper limit is3,000, and a particularly preferable upper limit is 2,500. If theaverage degree of polymerization satisfies the above preferable lowerlimit, the penetration resistance of a laminated glass can be furtherimproved. If the average degree of polymerization satisfies the abovepreferable upper limit, an intermediate film can be easily formed.

The average degree of polymerization of the polyvinyl alcohol resin forobtaining the polyvinyl acetal resin (1) contained in the first layer ispreferably higher than the average degree of polymerization of thepolyvinyl alcohol resin for obtaining the polyvinyl acetal resin (2) andthe polyvinyl acetal resin (3) contained in the second layer and thethird layer, preferably by 500 or higher, preferably by 800 or higher,more preferably by 1,000 or higher, still more preferably by 1,300 orhigher, and particularly preferably 1,800 or higher.

The average degree of polymerization of the polyvinyl alcohol can bedetermined in conformity with JIS K6726 “Testing methods for polyvinylalcohol”.

The carbon number of the acetal group contained in the polyvinyl acetalresin is not particularly limited. The aldehyde to be used uponproducing the polyvinyl acetal resin is not particularly limited. Thecarbon number of the acetal group in the polyvinyl acetal resin ispreferably 3 to 5, and more preferably 3 or 4. If the carbon number ofthe acetal group in the polyvinyl acetal resin is 3 or greater, theglass transition temperature of an intermediate film is sufficientlylow, so that the sound-insulating property against structure-borne soundat low temperatures can be further improved.

The aldehyde is not particularly limited. In general, a C1-C10 aldehydeis suitably used as the aforementioned aldehyde. Examples of the C1-C10aldehyde include propionaldehyde, n-butyl aldehyde, isobutyl aldehyde,n-valeraldehyde, 2-ethylbutyl aldehyde, n-hexyl aldehyde, n-octylaldehyde, n-nonyl aldehyde, n-decyl aldehyde, formaldehyde,acetaldehyde, and benzaldehyde. In particular, propionaldehyde, n-butylaldehyde, isobutyl aldehyde, n-hexyl aldehyde, or n-valeraldehyde ispreferable; propionaldehyde, n-butyl aldehyde, or isobutyl aldehyde ismore preferable; and n-butyl aldehyde is still more preferable. Each ofthe aldehydes may be used alone, or two or more of these may be used incombination.

The polyvinyl acetal resin is preferably a polyvinyl butyral resin. Theintermediate film for laminated glass of the present inventionpreferably contains a polyvinyl butyral resin as each of the polyvinylacetal resins contained in the first layer, the second layer and thethird layer. The polyvinyl butyral resin can be easily synthesized.Further, use of polyvinyl butyral resin allows an intermediate film tomore suitably exert its adhesive force to components for laminatedglass. In addition, properties such as the light resistance and weatherresistance can be further improved.

The hydroxy group content (hydroxy group amount) in the polyvinyl acetalresin (1) is preferably 45 mol % or lower, more preferably 35 mol % orlower, still more preferably 30 mol % or lower, much more preferably 25mol % or lower, particularly preferably 20 mol % or lower, and mostpreferably 15 mol % or lower. If the hydroxy group content is not higherthan the upper limit, the sound-insulating property of a laminated glasscan be further improved. In addition, the flexibility of an intermediatefilm can be improved and the intermediate film can be easily handled.From the viewpoint of further improving the sound-insulating property ina high frequency range of a laminated glass, the hydroxy group contentin the polyvinyl acetal resin (1) is preferably as low as possible. Thehydroxy group content in the polyvinyl acetal resin (1) can be 0 mol %.

The hydroxy group content (hydroxy group amount) in each of thepolyvinyl acetal resin (2) and the polyvinyl acetal resin (3) ispreferably higher than the hydroxy group content in the polyvinyl acetalresin (1). The hydroxy group content (hydroxy group amount) in each ofthe polyvinyl acetal resin (2) and the polyvinyl acetal resin (3) ispreferably 20 mol % or higher, more preferably 25 mol % or higher, andstill more preferably 30 mol % or higher, whereas preferably 50 mol % orlower, more preferably 45 mol % or lower, still more preferably 40 mol %or lower, and particularly preferably 35 mol % or lower. If the hydroxygroup content is not lower than the lower limit, the penetrationresistance of a laminated glass can be further improved. If the hydroxygroup content is not higher than the upper limit, bleed out of aplasticizer is less likely to occur. In addition, the flexibility of anintermediate film can be improved and the intermediate film may beeasily handled.

Each of the hydroxy group contents in the polyvinyl acetal resin (1),the polyvinyl acetal resin (2) and the polyvinyl acetal resin (3) is avalue of mole fraction in terms of percentage (mol %) obtained bydividing the amount of ethylene groups bonded with hydroxy groups by thetotal amount of ethylene groups in the main chain. The amount ofethylene groups bonded with hydroxy groups can be determined bymeasuring the amount of ethylene groups bonded with the hydroxy groupsin polyvinyl alcohol as a material in conformity with JIS K6726 “TestingMethods for Polyvinyl Alcohol”, for example.

The degree of acetalization of the polyvinyl acetal resin (1) (in thecase of polyvinyl butyral resin, degree of butyralization) is preferably20 mol % or higher, more preferably 25 mol % or higher, and still morepreferably 30 mol % or higher, whereas preferably 65 mol % or lower,more preferably 60 mol % or lower, and still more preferably 55 mol % orlower. If the degree of acetalization is not lower than the lower limit,the compatibility between the polyvinyl acetal resin (1) and theplasticizer can be improved, and bleed out of the plasticizer can besuppressed. If the degree of acetalization is not higher than the upperlimit, the reaction time required for producing a polyvinyl acetal resincan be shortened.

The degree of acetalization of each of the polyvinyl acetal resin (2)and the polyvinyl acetal resin (3) (in the case of polyvinyl butyralresin, degree of butyralization) is preferably 55 mol % or higher, morepreferably 60 mol % or higher, and still more preferably 63 mol % orhigher, whereas preferably 85 mol % or lower, more preferably 75 mol %or lower, and still more preferably 70 mol % or lower. If the degree ofacetalization is not lower than the lower limit, the compatibilitybetween the polyvinyl acetal resin (2) and the polyvinyl acetal resin(3) and the plasticizer can be improved. If the degree of acetalizationis not higher than the upper limit, the reaction time required forproducing a polyvinyl acetal resin can be shortened.

The degree of aetalization is a value of mole fraction in terms ofpercentage (mol %) obtained by dividing the amount of ethylene groupsbonded with acetal groups by the total amount of ethylene groups in themain chain.

The degree of acetalization can be calculated by measuring the degree ofacetylation (degree of acetylation) and the hydroxy group content (vinylalcohol amount), calculating the molar fractions thereof based on theobtained measurement results, and subtracting the degree of acetylationand the hydroxy group content from 100 mol %, according to the method inconformity with JIS K6728 “Testing Methods for Polyvinyl Butyral”.

The degree of acetalization can be calculated by measuring the degree ofacetylation (degree of acetylation) and the hydroxy group content (vinylalcohol amount), calculating the molar fractions thereof based on theobtained measurement results, and subtracting the degree of acetylationand the hydroxy group content from 100 mol %, according to the method inconformity with JIS K6728 “Testing Methods for Polyvinyl Butyral”.

In the case that the polyvinyl acetal resin is a polyvinyl butyralresin, the degree of acetalization (degree of butyralization) and thedegree of acetylation can be calculated based on the measurement resultsaccording to the method in conformity with JIS K6728 “Testing Methodsfor Polyvinyl Butyral” or ASTM D1396-92. It is preferable to measure thevalues according to the method in conformity with ASTM D1396-92.

With respect to the weight average molecular weight of each of thepolyvinyl acetal resin (1), the polyvinyl acetal resin (2) and thepolyvinyl acetal resin (3), the lower limit thereof is preferably100,000, and more preferably 300,000, whereas the upper limit thereof ispreferably 10,000,000, and more preferably 5,000,000. If the weightaverage molecular weight of the polyvinyl acetal resin is not higherthan the preferable lower limit, the strength of an intermediate filmmay be low. If the weight average molecular weight of the polyvinylacetal resin exceeds the preferable upper limit, the strength of anintermediate film to be obtained may be too high. The weight averagemolecular weight herein indicates a weight average molecular weight interms of polystyrene by gel permeation chromatography (GPC) measurement.

The aforementioned weight average molecular weight and number averagemolecular weight are a weight average molecular weight and a numberaverage molecular weight in terms of polystyrene obtained by gelpermeation chromatography (GPC) measurement. For example, in order tomeasure the weight average molecular weight and number average molecularweight in terms of polystyrene, polystyrene standard samples with knownmolecular weights are subjected to GPC measurement. As the polystyrenestandard samples (“Shodex Standard SM-105”, “Shodex Standard SH-75”,SHOWA DENKO K.K.) are used 14 samples with the respective weight averagemolecular weights of 580, 1,260, 2,960, 5,000, 10,100, 21,000, 28,500,76,600, 196,000, 630,000, 1,130,000, 2,190,000, 3,150,000, and3,900,000. Molecular weights are plotted with respect to thecorresponding elution times indicated by the peak tops of the peaks ofthe respective standard samples, and the obtained approximate straightline is used as a calibration curve. A multilayer intermediate film isleft in a constant temperature and humidity facility (humidity: 30%(±3%), temperature: 23° C.) for one month, and then the surface layers(the second layer and the third layer) and the intermediate layer (thefirst layer) are separated. The separated first layer (intermediatelayer) is dissolved in tetrahydrofuran (THF) to prepare a 0.1 wt %solution. The obtained solution is analyzed using a CPC device, andthereby the weight average molecular weight and the number averagemolecular weight are measured. The GPC device used for analyzing theweight average molecular weight and the number average molecular weightmay be a GPC device (Hitachi High-Technologies Corp., RI: L2490,auto-sampler: L-2200, pump: L-2130, column oven: L-2350, columns:GL-A120-S and GL-A100MX-S in series) connected with a light scatteringdetector for GPC (VISCOTEK, Model 270 (RALS+VISCO)).

(Method of Producing Polyvinyl Acetal Resin ContainingHigh-Molecular-Weight Component X with Absolute Molecular Weight of1,000,000 or Higher or High-Molecular-Weight Component Y with MolecularWeight y of 1,000,000 or Higher)

The following will describe in detail the method of producing apolyvinyl acetal resin containing a high-molecular-weight component Xwith an absolute molecular weight of 1,000,000 or higher or ahigh-molecular-weight component Y with a molecular weight y of 1,000,000or higher.

First, polyvinyl alcohol is prepared. The polyvinyl alcohol can beobtained by saponifying polyvinyl acetate, for example. The degree ofsaponification of the polyvinyl alcohol is usually within the range of70 to 99.9 mol %, preferably within the range of 75 to 99.8 mol %, andmore preferably within the range of 80 to 99.8 mol %.

With respect to the degree of polymerization of the polyvinyl alcohol, apreferable lower limit is 200, a more preferable lower limit is 500, astill more preferable lower limit is 1,000, and a particularlypreferable lower limit is 1,500, whereas a preferable upper limit is3,000, a more preferable upper limit is 2,900, a still more preferableupper limit is 2,800, and a particularly preferable upper limit is2,700. If the degree of polymerization is too low, the penetrationresistance of a laminated glass tends to be low. If the degree ofpolymerization is too high, it may be difficult to form an intermediatefilm.

Next, the polyvinyl alcohol and an aldehyde are reacted using acatalyst, and thereby the polyvinyl alcohol is acetalized. At this time,a solution containing the polyvinyl alcohol may be used. Examples of thesolvent used for the solution containing the polyvinyl alcohol includewater.

The method for producing the polyvinyl acetal resin contained in thefirst layer is preferably a production method in which the polyvinylalcohol and an aldehyde are reacted using a catalyst so that thepolyvinyl alcohol is acetalized, and thereby a polyvinyl acetal resin isobtained.

The method of producing the first layer preferably comprises a step ofpreparing a polyvinyl acetal resin by reacting a polyvinyl alcohol andan aldehyde using a catalyst so that the polyvinyl alcohol isacetalized, and a step of preparing the first layer using a mixture ofthe obtained polyvinyl acetal resin and a plasticizer. In this step ofpreparing the first layer, or after the first layer is obtained, amultilayer intermediate film can be obtained by laminating a secondlayer and, if necessary, laminating a third layer, on the first layer.Alternatively, a multilayer intermediate film can be produced byco-extruding the first layer and the second layer, or a multilayerintermediate film can be produced by co-extruding the first layer, thesecond layer, and the third layer.

The aldehyde is not particularly limited. A suitable aldehyde iscommonly a C1-C10 aldehyde. Examples of the C1-C10 aldehyde includepropionaldehyde, n-butyl aldehyde, isobutyl aldehyde, n-valeraldehyde,2-ethylbutyl aldehyde, n-hexyl aldehyde, n-octyl aldehyde, n-nonylaldehyde, n-decyl aldehyde, formaldehyde, acetaldehyde, andbenzaldehyde. In particular, n-butyl aldehyde, n-hexyl aldehyde, orn-valeraldehyde is preferable, and n-butyl aldehyde is more preferable.Each of the aldehydes may be used alone, or two or more of these may beused in combination.

From the viewpoint of easily obtaining a polyvinyl acetal resincontaining high-molecular-weight component X with an absolute molecularweight of 1,000,000 or higher or high-molecular-weight component Y witha molecular weight y of 1,000,000 or higher in the aforementionedspecific ratio, for example, the following methods can be exemplified: amethod of adding a cross-linker such as dialdehyde for cross-linking themain chains of adjacent polyvinyl alcohols before or in the middle ofthe acetalizing reaction with an aldehyde; a method of adding anexcessive amount of aldehyde to proceed the acetalizing reaction betweenthe molecules; and a method of adding a polyvinyl alcohol with a highdegree of polymerization. Each of these methods may be used alone, ortwo or more of these may be used in combination.

The catalyst is preferably an acid catalyst. Examples of the acidcatalyst include nitric acid, hydrochloric acid, sulfuric acid,phosphoric acid, and para-toluenesulfonic acid.

The molecular weight in terms of polystyrene is a molecular weight interms of polystyrene by gel permeation chromatography (GPC) measurement.The proportion (%) of the high-molecular-weight component Y with amolecular weight y of 1,000,000 or higher in the polyvinyl acetal resinis calculated from the ratio of the area corresponding to a region wherethe molecular weight y is 1,000,000 or higher among the peak areadetected by an RI detector upon measuring the molecular weight in termsof polystyrene by GPC on the polyvinyl acetal resin. The peak area meansan area between the peak and the baseline of the component to bemeasured.

The molecular weight in terms of polystyrene can be measured as follows,for example.

In order to measure the molecular weight in terms of polystyrenestandard, polystyrene standard samples with known molecular weights aresubjected to GPC measurement. As the polystyrene standard samples(“Shodex Standard SM-105”, “Shodex Standard SH-75”, SHOWA DENKO K.K.)are used 14 samples with the respective weight average molecular weightsof 580, 1,260, 2,960, 5,000, 10,100, 21,000, 28,500, 76,600, 196,000,630,000, 1,130,000, 2,190,000, 3,150,000, and 3,900,000. Weight averagemolecular weights are plotted with respect to the corresponding elutiontimes indicated by the peak tops of the peaks of the respective standardsamples, and the obtained approximate straight line is used as acalibration curve. In the case of measuring the proportion (%) of thehigh-molecular-weight component Y with the molecular weight y of1,000,000 or higher in the polyvinyl acetal resin contained in theintermediate layer in a multilayer intermediate film having a surfacelayer, the intermediate layer, and a surface layer laminated in thestated order, for example, the multilayer intermediate film is left in aconstant temperature and humidity facility (humidity: 30% (±3%),temperature: 23° C.) for one month, and then the surface layers and theintermediate layer are separated. The separated intermediate layer isdissolved in tetrahydrofuran (THF) to prepare a 0.1 wt % solution. Theobtained solution is analyzed using a GPC device, and thereby the peakarea of the polyvinyl acetal resin in the intermediate layer ismeasured. Next, based on the elution time and the calibration curve ofthe polyvinyl acetal resin contained in the intermediate layer, the areacorresponding to a region where the molecular weight in terms ofpolystyrene of the polyvinyl acetal resin contained in the intermediatelayer is 1,000,000 or higher is calculated. By representing inpercentage (%) a value obtained by dividing the area corresponding to aregion where the molecular weight in terms of polystyrene of thepolyvinyl acetal resin contained in the intermediate layer is 1,000,000or higher by the peak area of the polyvinyl acetal resin contained inthe intermediate layer, the proportion (%) of the high-molecular-weightcomponent Y with the molecular weight y of 1,000,000 or higher in thepolyvinyl acetal resin can be calculated. For example, the molecularweight in terms of polystyrene can be measured using a gel permeationchromatography (GPC) device (Hitachi High-Technologies Corp., RI: L2490,auto-sampler: L-2200, pump: L-2130, column oven: L-2350, columns:GL-A120-S and GL-A100MX-S in series).

(Plasticizer)

The first layer contains a plasticizer (hereinafter, also referred to asa plasticizer (1)). The second layer preferably contains a plasticizer(hereinafter, also referred to as a plasticizer (2)). The third layerpreferably contains a plasticizer (hereinafter, also referred to as aplasticizer (3)). The plasticizer (1), the plasticizer (2) and theplasticizer (3) contained in the first layer, the second layer and thethird layer are not particularly limited. Conventionally knownplasticizers can be used as the plasticizer (1), the plasticizer (2) andthe plasticizer (3). Each of the plasticizer (1), the plasticizer (2)and the plasticizer (3) may be used alone, or two or more of these maybe used in combination.

Examples of the plasticizer (1), the plasticizer (2) and the plasticizer(3) include organic ester plasticizers such as monobasic organic acidesters and polybasic organic acid esters, and phosphate plasticizerssuch as organophosphate plasticizers and organophosphite plasticizers.Preferable among these are organic ester plasticizers. The plasticizersare preferably liquid plasticizers.

The monobasic organic acid esters are not particularly limited. Examplesthereof include glycol esters obtainable by reaction of a glycol and amonobasic organic acid, and esters of triethylene glycol or tripropyleneglycol and a monobasic organic acid. Examples of the glycol includetriethylene glycol, tetraethylene glycol, and tripropylene glycol.Examples of the monobasic organic acid include butyric acid, isobutyricacid, caproic acid, 2-ethylbutyric acid, heptanoic acid, n-octylic acid,2-ethylhexylic acid, n-nonylic acid, and decylic acid.

The polybasic organic acid esters are not particularly limited. Examplesthereof include ester compounds of a polybasic organic acid and a C4-C8linear or branched alcohol. Examples of the polybasic organic acidinclude adipic acid, sebacic acid, and azelaic acid.

The organic ester plasticizers are not particularly limited. Examplesthereof include triethylene glycol di-2-ethyl butyrate, triethyleneglycol di-2-ethyl hexanoate, triethylene glycol dicaprylate, triethyleneglycol di-n-octanoate, triethylene glycol di-n-heptanoate, tetraethyleneglycol di-n-heptanoate, dibutyl sebacate, dioctyl azelate, dibutylcarbitol adipate, ethylene glycol di-2-ethyl butyrate, 1,3-propyleneglycol di-2-ethyl butyrate, 1,4-butyrene glycol di-2-ethyl butyrate,diethylene glycol di-2-ethyl butyrate, diethylene glycol di-2-ethylhexanoate, dipropylene glycol di-2-ethyl butyrate, triethylene glycoldi-2-ethyl pentanoate, tetraethylene glycol di-2-ethyl butyrate,diethylene glycol dicaprylate, dihexyl adipate, dioctyl adipate, hexylcyclohexyl adipate, a mixture of heptyl adipate and nonyl adipate,diisononyl adipate, diisodecyl adipate, heptylnonyl adipate, dibutylsebacate, oil-modified alkyd sebacate, and a mixture of a phosphate andan adipate. Organic ester plasticizers other than these may also beused.

The organophosphate plasticizers are not particularly limited. Examplesthereof include tributoxyethyl phosphate, isodecylphenyl phosphate, andtriisopropyl phosphate.

The plasticizer (1), the plasticizer (2) and the plasticizer (3) eachare preferably a diester plasticizer represented by the followingformula (1).

In the formula (1), R1 and R2 each represent a C3-C10 organic group; R3represents an ethylene group, an isopropylene group, or an n-propylenegroup; and p is an integer of 3 to 10. In the formula (1), R1 and R2each are preferably a C5-C10 alkyl group.

The plasticizers preferably include at least one of triethylene glycoldi-2-ethyl hexanoate (3GO), triethylene glycol dibutyrate (3GB), dibutyladipate, and triethylene glycol di-2-ethyl butyrate (3GH), and morepreferably include triethylene glycol di-2-ethyl hexanoate ortriethylene glycol dibutyrate.

In the first layer, the amount of the plasticizer (1) is preferably 25to 60 parts by weight for each 100 parts by weight of the polyvinylacetal resin (1). The amount of the plasticizer (1) for each 100 partsby weight of the polyvinyl acetal resin (1) is more preferably 30 partsby weight or more, and still more preferably 40 parts by weight or more,whereas more preferably 55 parts by weight or less, and still morepreferably 50 parts by weight or less. If the amount of the plasticizer(1) is not lower than the lower limit, the flexibility of anintermediate film may be high, and thereby the intermediate film can beeasily handled. If the amount of the plasticizer (1) is not higher thanthe upper limit, the transparency of an intermediate film can be higher.

In the second layer (2), the amount of the plasticizer (2) is preferably15 to 45 parts by weight for each 100 parts by weight of the polyvinylacetal resin (2). In addition, in the third layer (3), the amount of theplasticizer (3) is preferably 15 to 45 parts by weight for each 100parts by weight of the polyvinyl acetal resin (3). The amount of each ofthe plasticizer (2) and the plasticizer (3) for each 100 parts by weightof the polyvinyl acetal resin (2) and the polyvinyl acetal resin (3) ismore preferably 20 parts by weight or more, whereas more preferably 40parts by weight or less. If each of the amounts of the plasticizer (2)and the plasticizer (3) is not lower than the lower limit, theflexibility of an intermediate film may be high, and thereby theintermediate film can be easily handled. If each of the amounts of theplasticizer (2) and the plasticizer (3) is not higher than the upperlimit, the penetration resistance of an intermediate film can be higher.

The amount of the plasticizer (2) (hereinafter, also referred to as anamount (2)) for each 100 parts by weight of the polyvinyl acetal resin(2) in the second layer is preferably less than the amount of theplasticizer (1) (hereinafter, also referred to as an amount (1)) foreach 100 parts by weight of the polyvinyl acetal resin (1) in the firstlayer. Also, the amount of the plasticizer (3) (hereinafter, alsoreferred to as an amount (3)) for each 100 parts by weight of thepolyvinyl acetal resin (3) in the third layer is preferably less thanthe amount of the plasticizer (1) (hereinafter, also referred to as anamount (1)) for each 100 parts by weight of the polyvinyl acetal resin(1) in the first layer. As the amount (2) and the amount (3) each areless than the amount (1), the penetration resistance of a laminatedglass can be higher.

With respect to the difference between the amount (1) and each of theamount (2) and the amount (3), a preferable lower limit is 1 part byweight, a more preferable lower limit is 5 parts by weight, a still morepreferable lower limit is 10 parts by weight, a particularly preferablelower limit is 15 parts by weight, and a most preferable lower limit is20 parts by weight, whereas a preferable upper limit is 40 parts byweight, a more preferable upper limit is 35 parts by weight, a stillmore preferable upper limit is 30 parts by weight, and a particularlypreferable upper limit is 25 parts by weight. If the difference betweenthe amount (1) and each of the amount (2) and the amount (3) is notlower than the lower limit, the sound-insulating property of a laminatedglass can be higher, whereas if the difference is not higher than theupper limit, the penetration resistance of a laminated glass can behigher. The difference between the amount (1) and each of the amount (2)and the amount (3) is a value obtained by subtracting either the amount(2) or the amount (3) from the amount (1).

(Other Components)

The intermediate film for laminated glass of the present invention maycontain additives such as an ultraviolet absorber, an antioxidant, aphotostabilizer, a flame retardant, an antistatic agent, pigments, dyes,adhesiveness adjuster, an anti-humidity agent, a fluorescent brightener,and an infrared radiation absorber, if necessary. Each of theseadditives may be used alone, or two or more additives may be used incombination.

(Intermediate Film for Laminated Glass)

The thickness of the first layer is preferably within a range of 0.02 to1.8 mm. The thickness of the first layer is more preferably 0.05 mm orhigher, and still more preferably 0.08 mm or higher, whereas morepreferably 0.5 mm or lower, and still more preferably 0.15 mm or lower.

As the first layer has such a preferable thickness, an intermediate filmmay not be too thick, and the sound-insulating property of theintermediate film and a laminated glass can be further improved.

The thicknesses of the second layer and the third layer each arepreferably within a range of 0.1 to 1 mm. The thicknesses of the secondlayer and the third layer each are more preferably 0.2 mm or higher, andstill more preferably 0.3 mm or higher, whereas more preferably 0.5 mmor lower, and still more preferably 0.4 mm or lower. If the thicknessesof the second layer and the third layer each are not lower than thelower limit and not higher than the upper limit, an intermediate filmmay not be too thick, the sound-insulating property of the intermediatefilm and a laminated glass can be further improved, and bleed out of theplasticizers can be suppressed.

In the case that the intermediate film has a laminated structure of twoor more layers, as the ratio of the thickness of the first layer to thethickness of the intermediate film ((thickness of firstlayer)/(thickness of intermediate film)) is smaller and the amount ofthe plasticizer contained in the first layer is larger, bubble formationand bubble growth in a laminated glass is more likely to occur and thebubbles are more likely to grow. Particularly in the case that the ratioin the intermediate film is 0.05 or higher and 0.35 or lower, bubbleformation and bubble growth in a laminated glass can be sufficientlysuppressed and the sound-insulating property of a laminated glass can befurther improved even though the amount of the plasticizer for each 100parts by weight of the polyvinyl acetal resin is large in the firstlayer. The ratio ((thickness of first layer)/(thickness of intermediatefilm)) is preferably 0.06 or higher, more preferably 0.07 or higher,still more preferably 0.08 or higher, and particularly preferably 0.1 orhigher, whereas preferably 0.3 or lower, more preferably 0.25 or lower,still more preferably 0.2 or lower, and particularly preferably 0.15 orlower.

The thickness of the intermediate film for laminated glass of thepresent invention is preferably within a range of 0.1 to 3 mm. Thethickness of the intermediate film is more preferably 0.25 mm or higher,whereas more preferably 1.5 mm or lower. If the thickness of theintermediate film is not lower than the lower limit, the penetrationresistance of the intermediate film and a laminated glass may besufficiently high. If the thickness of the intermediate film is nothigher than the upper limit, the transparency of an intermediate filmmay be better.

The method for producing the intermediate film for laminated glass ofthe present invention is not particularly limited. Any conventionallyknown method may be used as the method for producing the intermediatefilm. For example, a polyvinyl acetal resin and a plasticizer, and othercomponents added as appropriate are kneaded, and then the kneadedproduct is formed into an intermediate film. A production methodincluding extrusion-molding is preferable because such a method issuitable for continuous production.

The kneading method is not particularly limited. For example, a methodusing an extruder, a plastograph, a kneader, a Banbury mixer, or acalender roll may be applied. Preferable among these is a method usingan extruder, and a method using a twin-screw extruder is more suitablebecause it is suitable for continuous production. With respect to theintermediate film for laminated glass of the present invention, thefirst layer, the second layer and the third layer may be separatelyproduced, and then laminated to provide a multilayer intermediate film,or the first layer, the second layer and the third layer may belaminated by co-extrusion to provide an intermediate film.

Because the producibility of the intermediate film is excellent, thesecond layer and the third layer preferably contain the same polyvinylacetal resin; the second layer and the third layer more preferablycontain the same polyvinyl acetal resin and the same plasticizer; andthe second layer and the third layer are still more preferably formedfrom the same resin composition.

(Laminated Glass)

FIG. 2 is a cross-sectional view showing one example of a laminatedglass using the intermediate film for laminated glass according to oneembodiment of the present invention.

A laminated glass 11 shown in FIG. 2 comprises an intermediate film 1, afirst component for laminated glass 21 and a second component forlaminated glass 22.

The intermediate film 1 is sandwiched between the first component forlaminated glass 21 and the second component for laminated glass 22. Thecomponent for laminated glass 21 is laminated on a first surface 1 a ofthe intermediate film 1. The component for laminated glass 22 islaminated on a second surface 1 b opposite to the first surface 1 a ofthe intermediate film 1. The first component for laminated glass 21 islaminated on an outer surface 3 a of the second layer 3. The secondcomponent for laminated glass 22 is laminated on an outer surface 4 a ofthe third layer 4.

As mentioned above, the laminated glass of the present inventioncomprises a first component for laminated glass, a second component forlaminated glass, and an intermediate film sandwiched between the firstcomponent for laminated glass and the second component for laminatedglass, wherein the intermediate film is the intermediate film forlaminated glass of the present invention.

Examples of the first component for laminated glass and the secondcomponent for laminated glass include glass plates and PET (polyethyleneterephthalate) films.

The laminated glass includes not only a laminated glass in which anintermediate film is sandwiched between two glass plates, but also alaminated glass in which an intermediate film is sandwiched between aglass plate and a PET film, for example. The laminated glass is alaminate comprising a glass plate, and at least one glass plate ispreferably used.

Examples of the glass plate include inorganic glass and organic glass.Examples of the inorganic glass include float plate glass,heat-absorbing plate glass, heat-reflective plate glass, polished plateglass, patterned glass, wired glass, linear-wired glass and green-tintedglass. The organic glass is synthetic resin glass used instead ofinorganic glass. Examples of the organic glass include polycarbonateplates and poly(meth)acryl resin plates. Examples of the poly(meth)acrylresin plate include polymethyl(meth)acrylate plates.

The thickness of each of the first component for laminated glass and thesecond component for laminated glass is not particularly limited, and itis preferably within a range of 1 to 5 mm. In the case that thecomponent for laminated glass is a glass plate, the thickness of theglass plate is preferably within a range of 1 to 5 mm. In the case thatthe component for laminated glass is a PET film, the thickness of thePET film is preferably within a range of 0.03 to 0.5 mm.

The method for producing the laminated glass is not particularlylimited. For example, the intermediate film is sandwiched between thefirst component for laminated glass and the second component forlaminated glass, and then passed through a press roll or put into arubber bag and decompression-sucked, so that the air remained betweenthe first component for laminated glass and the second component forlaminated glass and the intermediate film is removed. Thereafter, theworkpiece is pre-bonded at about 70° C. to 110° C. so that a laminate isprovided. Next, the laminate is put into an autoclave or pressed so thatthe laminate is press-bonded at about 120° C. to 150° C. and a pressureof 1 to 1.5 MPa, and thereby a laminated glass is obtained.

The laminated glass can be used for automobiles, railway carriages,aircrafts, ships, buildings, and the like. The laminated glass can alsobe used for other applications. The intermediate film is preferably anintermediate film for buildings or vehicles, and more preferably forvehicles. The laminated glass is preferably a laminated glass forbuildings or vehicles, and more preferably for vehicles. Theintermediate film and the laminated glass can be suitably used forelectric vehicles using electric motors and hybrid electric vehiclesusing internal-combustion engines and electric motors. The laminatedglass can be used for windshields, side glasses, rear glasses, and roofglasses of automobiles.

The following will describe the present invention in detail referringto, but not limited to, examples.

In the examples and comparative examples, the following polyvinylbutyral resins (polyvinyl acetal resins) were used. The degree ofbutyralization (degree of acetalization), the degree of acetylation, andthe hydroxy group content of each polyvinyl butyral resin were measuredby the method in conformity with ASTM D1396-92. Also, in the case ofmeasuring the values in conformity with JIS K6728 “Testing Methods forPolyvinyl Butyral”, the same values were indicated as in the method inconformity with ASTM D1396-92.

Synthesis Example 1 Synthesis of Polyvinyl Butyral Resin a

A polyvinyl butyral resin (average degree of polymerization: 3,000)having a degree of acetylation of 0.5 mol %, a degree of butyralizationof 40 mol %, and a hydroxy group content of 59.5 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 30 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin a (average degree of polymerization: 3,000) was obtained.With respect to the obtained polyvinyl butyral resin a, the degree ofacetylation was 30.5 mol %, the degree of butyralization was 40 mol %,and the hydroxy group content was 29.5 mol %.

Synthesis Example 2 Synthesis of Polyvinyl Butyral Resin b

A polyvinyl butyral resin (average degree of polymerization: 3,000)having a degree of acetylation of 0.5 mol %, a degree of butyralizationof 35 mol %, and a hydroxy group content of 64.5 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 39.5 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin b (average degree of polymerization: 3,000) was obtained.With respect to the obtained polyvinyl butyral resin b, the degree ofacetylation was 40 mol %, the degree of butyralization was 35 mol %, andthe hydroxy group content was 25 mol %.

Synthesis Example 3 Synthesis of Polyvinyl Butyral Resin c

A polyvinyl butyral resin (average degree of polymerization: 3,000)having a degree of acetylation of 0.5 mol %, a degree of butyralizationof 25 mol %, and a hydroxy group content of 74.5 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 49.5 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin c (average degree of polymerization: 3,000) was obtained.With respect to the obtained polyvinyl butyral resin c, the degree ofacetylation was 50 mol %, the degree of butyralization was 25 mol %, andthe hydroxy group content was 25 mol %.

Synthesis Example 4 Synthesis of Polyvinyl Butyral Resin d

To 2,910 g of pure water was added 190 g of polyvinyl alcohol with adegree of polymerization of 1,700, and then the mixture was heated sothat the polyvinyl alcohol was dissolved into the pure water. Thetemperature of the solution was controlled to 12° C. To the solutionwere added 201 g of 35 wt % hydrochloric acid and 134 g of n-butylaldehyde, and a polyvinyl butyral resin was precipitated. Thereafter,the reaction system was kept at 50° C. for 4 hours, and the reaction wasfinished. The resin was washed with excess water so that unreactedn-butyl aldehyde was washed away. Further, the hydrochloric acidcatalyst was neutralized and the salt was removed, and then the productwas dried. Thereby, a polyvinyl butyral resin d was obtained. Withrespect to the obtained polyvinyl butyral resin d, the degree ofacetylation was 1 mol %, the degree of butyralization was 68.5 mol %,and the hydroxy group content was 30.5 mol %.

Synthesis Example 5 Synthesis of Polyvinyl Butyral Resin e

To 2,890 g of pure water was added 191 g of polyvinyl alcohol with adegree of polymerization of 3,000, and then the mixture was heated sothat the polyvinyl alcohol was dissolved into the pure water. Thetemperature of the solution was controlled to 12° C. To the solutionwere added 201 g of 35 wt % hydrochloric acid and 150 g of n-butylaldehyde, and a polyvinyl butyral resin was precipitated. Thereafter,the reaction system was kept at 50° C. for 5 hours, and the reaction wasfinished. The resin was washed with excess water so that unreactedn-butyl aldehyde was washed away. Further, the hydrochloric acidcatalyst was neutralized and the salt was removed, and then the productwas dried. Thereby, a polyvinyl butyral resin e was obtained. Withrespect to the obtained polyvinyl butyral resin e, the degree ofacetylation was 12.8 mol %, the degree of butyralization was 63.5 mol %,and the hydroxy group content was 23.7 mol %.

Synthesis Example 6 Synthesis of Polyvinyl Butyral Resin f

A polyvinyl butyral resin (average degree of polymerization: 3,000)having a degree of acetylation of 13 mol %, a degree of butyralizationof 59 mol %, and a hydroxy group content of 28 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 22 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin f was obtained. With respect to the obtained polyvinylbutyral resin f, the degree of acetylation was 35 mol %, the degree ofbutyralization was 59 mol %, and the hydroxy group content was 6 mol %.

Synthesis Example 7 Synthesis of Polyvinyl Butyral Resin g

A polyvinyl butyral resin (average degree of polymerization: 3,000)having a degree of acetylation of 20 mol %, a degree of butyralizationof 45 mol %, and a hydroxy group content of 35 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 20 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin g was obtained. With respect to the obtained polyvinylbutyral resin g, the degree of acetylation was 40 mol %, the degree ofbutyralization was 45 mol %, and the hydroxy group content was 15 mol %.

Synthesis Example 8 Synthesis of Polyvinyl Butyral Resin h

A blended product (weight ratio is 1:1) of a polyvinyl butyral resin(average degree of polymerization: 2,800) with a degree of acetylationof 20 mol %, a degree of butyralization of 58 mol %, and a hydroxy groupcontent of 22 mol % and a polyvinyl butyral resin (average degree ofpolymerization: 4,000) with a degree of acetylation of 20 mol %, adegree of butyralization of 58 mol %, and a hydroxy group content of 22mol % was dissolved in pyridine. To the dissolved polyvinyl butyralresins was added 15 mol equivalents of acetic anhydride, and the mixturewas stirred at 80° C. for 120 minutes. The pyridine was removed, andthen the polyvinyl butyral resin was washed with water and dried.Thereby, a polyvinyl butyral resin h was obtained. With respect to theobtained polyvinyl butyral resin h, the degree of acetylation was 35 mol%, the degree of butyralization was 58 mol %, and the hydroxy groupcontent was 7 mol %. The proportion of the high-molecular-weightcomponent X (polyvinyl butyral resin) with an absolute molecular weightof 1,000,000 or higher was 19.6% in the obtained polyvinyl butyralresin. The proportion of the high-molecular-weight component Y(polyvinyl butyral resin) with a molecular weight y of 1,000,000 orhigher was 23.1% in the obtained polyvinyl butyral resin Z.

Synthesis Example 9 Synthesis of Polyvinyl Butyral Resin i

A polyvinyl butyral resin (average degree of polymerization: 3,050)having a degree of acetylation of 20 mol %, a degree of butyralizationof 26 mol %, and a hydroxy group content of 54 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 47 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin i was obtained. With respect to the obtained polyvinylbutyral resin i, the degree of acetylation was 67 mol %, the degree ofbutyralization was 26 mol %, and the hydroxy group content was 7 mol %.

Synthesis Example 10 Synthesis of Polyvinyl Butyral Resin j

A polyvinyl butyral resin (average degree of polymerization: 3,050)having a degree of acetylation of 30 mol %, a degree of butyralizationof 13 mol %, and a hydroxy group content of 57 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 50 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin j was obtained. With respect to the obtained polyvinylbutyral resin j, the degree of acetylation was 80 mol %, the degree ofbutyralization was 13 mol %, and the hydroxy group content was 7 mol %.

Synthesis Example 11 Synthesis of Polyvinyl Butyral Resin k

A polyvinyl butyral resin (average degree of polymerization: 3,200)having a degree of acetylation of 20 mol %, a degree of butyralizationof 58 mol %, and a hydroxy group content of 22 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 20 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin k was obtained. With respect to the obtained polyvinylbutyral resin k, the degree of acetylation was 40 mol %, the degree ofbutyralization was 58 mol %, and the hydroxy group content was 2 mol %.

Synthesis Example 12 Synthesis of Polyvinyl Butyral Resin l

A polyvinyl butyral resin (average degree of polymerization: 3,200)having a degree of acetylation of 20 mol %, a degree of butyralizationof 52 mol %, and a hydroxy group content of 28 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 12 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin l was obtained. With respect to the obtained polyvinylbutyral resin l, the degree of acetylation was 32 mol %, the degree ofbutyralization was 52 mol %, and the hydroxy group content was 16 mol %.

Synthesis Example 13 Synthesis of Polyvinyl Butyral Resin m

A polyvinyl butyral resin (average degree of polymerization: 3,200)having a degree of acetylation of 20 mol %, a degree of butyralizationof 50 mol %, and a hydroxy group content of 30 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 10.5 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin m was obtained. With respect to the obtained polyvinylbutyral resin m, the degree of acetylation was 30.5 mol %, the degree ofbutyralization was 50 mol %, and the hydroxy group content was 19.5 mol%.

Synthesis Example 14 Synthesis of Polyvinyl Butyral Resin n

A polyvinyl butyral resin (average degree of polymerization: 3,200)having a degree of acetylation of 20 mol %, a degree of butyralizationof 55 mol %, and a hydroxy group content of 25 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 10.5 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin n was obtained. With respect to the obtained polyvinylbutyral resin n, the degree of acetylation was 30.5 mol %, the degree ofbutyralization was 55 mol %, and the hydroxy group content was 14.5 mol%.

Synthesis Example 15 Synthesis of Polyvinyl Butyral Resin q

A polyvinyl butyral resin (average degree of polymerization: 3,000)having a degree of acetylation of 10 mol %, a degree of butyralizationof 65 mol %, and a hydroxy group content of 25 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 20.5 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin q was obtained. With respect to the obtained polyvinylbutyral resin q, the degree of acetylation was 30.5 mol %, the degree ofbutyralization was 65 mol %, and the hydroxy group content was 4.5 mol%.

Synthesis Example 16 Synthesis of Polyvinyl Butyral Resin r

A polyvinyl butyral resin (average degree of polymerization: 3,200)having a degree of acetylation of 30 mol %, a degree of butyralizationof 45 mol %, and a hydroxy group content of 25 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 10 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin r was obtained. With respect to the obtained polyvinylbutyral resin r, the degree of acetylation was 40 mol %, the degree ofbutyralization was 45 mol %, and the hydroxy group content was 15 mol %.

Synthesis Example 17 Synthesis of Polyvinyl Butyral Resin t

A polyvinyl butyral resin (average degree of polymerization: 3,200)having a degree of acetylation of 20 mol %, a degree of butyralizationof 50 mol %, and a hydroxy group content of 30 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 20 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin t was obtained. With respect to the obtained polyvinylbutyral resin t, the degree of acetylation was 40 mol %, the degree ofbutyralization was 50 mol %, and the hydroxy group content was 10 mol %.

Synthesis Example 18 Synthesis of Polyvinyl Butyral Resin u

A polyvinyl butyral resin (average degree of polymerization: 3,200)having a degree of acetylation of 20 mol %, a degree of butyralizationof 45 mol %, and a hydroxy group content of 35 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 30.7 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin u was obtained. With respect to the obtained polyvinylbutyral resin u, the degree of acetylation was 50.7 mol %, the degree ofbutyralization was 45 mol %, and the hydroxy group content was 4.3 mol%.

Synthesis Example 19 Synthesis of Polyvinyl Butyral Resin v

A polyvinyl butyral resin (average degree of polymerization: 3,200)having a degree of acetylation of 30 mol %, a degree of butyralizationof 33.5 mol %, and a hydroxy group content of 36.5 mol % was dissolvedin pyridine. To the dissolved polyvinyl butyral resin was added 20.2 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin v was obtained. With respect to the obtained polyvinylbutyral resin v, the degree of acetylation was 50.2 mol %, the degree ofbutyralization was 33.5 mol %, and the hydroxy group content was 16.3mol %.

Synthesis Example 20 Synthesis of Polyvinyl Butyral Resin w

A polyvinyl butyral resin (average degree of polymerization: 3,200)having a degree of acetylation of 30 mol %, a degree of butyralizationof 28.4 mol %, and a hydroxy group content of 41.6 mol % was dissolvedin pyridine. To the dissolved polyvinyl butyral resin was added 20.5 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin w was obtained. With respect to the obtained polyvinylbutyral resin w, the degree of acetylation was 50.5 mol %, the degree ofbutyralization was 28.4 mol %, and the hydroxy group content was 21.1mol %.

Synthesis Example 21 Synthesis of Polyvinyl Butyral Resin x

A polyvinyl butyral resin (average degree of polymerization: 3,200)having a degree of acetylation of 30 mol %, a degree of butyralizationof 35 mol %, and a hydroxy group content of 35 mol % was dissolved inpyridine. To the dissolved polyvinyl butyral resin was added 30 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin x was obtained. With respect to the obtained polyvinylbutyral resin x, the degree of acetylation was 60 mol %, the degree ofbutyralization was 35 mol %, and the hydroxy group content was 5 mol %.

Synthesis Example 22 Synthesis of Polyvinyl Butyral Resin y

A polyvinyl butyral resin (average degree of polymerization: 3,200)having a degree of acetylation of 30 mol %, a degree of butyralizationof 29.5 mol %, and a hydroxy group content of 40.5 mol % was dissolvedin pyridine. To the dissolved polyvinyl butyral resin was added 30 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin y was obtained. With respect to the obtained polyvinylbutyral resin y, the degree of acetylation was 60 mol %, the degree ofbutyralization was 29.5 mol %, and the hydroxy group content was 10.5mol %.

Synthesis Example 23 Synthesis of Polyvinyl Butyral Resin z

A polyvinyl butyral resin (average degree of polymerization: 3,200)having a degree of acetylation of 30 mol %, a degree of butyralizationof 24.3 mol %, and a hydroxy group content of 45.7 mol % was dissolvedin pyridine. To the dissolved polyvinyl butyral resin was added 30 molequivalents of acetic anhydride, and the mixture was stirred at 80° C.for 120 minutes. The pyridine was removed, and then the polyvinylbutyral resin was washed with water and dried. Thereby, a polyvinylbutyral resin z was obtained. With respect to the obtained polyvinylbutyral resin z, the degree of acetylation was 60 mol %, the degree ofbutyralization was 24.3 mol %, and the hydroxy group content was 15.7mol %.

Synthesis Example 24 Synthesis of Polyvinyl Butyral Resin o

To 3,000 g of pure water was added 190 g of polyvinyl alcohol with adegree of saponification of 98.2% and a degree of polymerization of1,700, and then the mixture was heated so that the polyvinyl alcohol wasdissolved into the pure water. The temperature of the solution wascontrolled to 12° C. To the solution were added 212 g of 35 wt %hydrochloric acid and 136 g of n-butyl aldehyde, and a polyvinyl butyralresin was precipitated. Thereafter, the reaction system was kept at 50°C. for 4 hours, and the reaction was finished. The resin was washed withexcess water so that unreacted n-butyl aldehyde was washed away.Further, the hydrochloric acid catalyst was neutralized and the salt wasremoved, and then the product was dried. Thereby, a polyvinyl butyralresin o was obtained. With respect to the obtained polyvinyl butyralresin o, the degree of acetylation was 1.8 mol %, the degree ofbutyralization was 68.5 mol %, and the hydroxy group content was 29.7mol %.

Synthesis Example 25 Synthesis of Polyvinyl Butyral Resin p

To 3,000 g of pure water was added 190 g of polyvinyl alcohol with adegree of saponification of 98.8% and a degree of polymerization of1,700, and then the mixture was heated so that the polyvinyl alcohol wasdissolved into the pure water. The temperature of the solution wascontrolled to 12° C. To the solution were added 206 g of 35 wt %hydrochloric acid and 142 g of n-butyl aldehyde, and a polyvinyl butyralresin was precipitated. Thereafter, the reaction system was kept at 50°C. for 4 hours, and the reaction was finished. The resin was washed withexcess water so that unreacted n-butyl aldehyde was washed away.Further, the hydrochloric acid catalyst was neutralized and the salt wasremoved, and then the product was dried. Thereby, a polyvinyl butyralresin p was obtained. With respect to the obtained polyvinyl butyralresin p, the degree of acetylation was 1.2 mol %, the degree ofbutyralization was 72.4 mol %, and the hydroxy group content was 26.4mol %.

Synthesis Example 26 Synthesis of Polyvinyl Butyral Resin s

To 2,910 g of pure water was added 190 g of polyvinyl alcohol with adegree of polymerization of 1,700, and then the mixture was heated sothat the polyvinyl alcohol was dissolved into the pure water. Thetemperature of the solution was controlled to 12° C. To the solutionwere added 201 g of 35 wt % hydrochloric acid and 122 g of n-butylaldehyde, and a polyvinyl butyral resin was precipitated. Thereafter,the reaction system was kept at 50° C. for 4 hours, and the reaction wasfinished. The resin was washed with excess water so that unreactedn-butyl aldehyde was washed away. Further, the hydrochloric acidcatalyst was neutralized and the salt was removed, and then the productwas dried. Thereby, a polyvinyl butyral resin s was obtained. Withrespect to the obtained polyvinyl butyral resin s, the degree ofacetylation was 1 mol %, the degree of butyralization was 62.5 mol %,and the hydroxy group content was 36.5 mol %.

Synthesis Example 27 Synthesis of Polyvinyl Butyral Resin AA

To 3,000 g of pure water was added 190 g of polyvinyl alcohol with adegree of saponification of 99.0% and a degree of polymerization of1,700, and then the mixture was heated so that the polyvinyl alcohol wasdissolved into the pure water. The temperature of the solution wascontrolled to 12° C. To the solution were added 212 g of 35 wt %hydrochloric acid and 124 g of n-butyl aldehyde, and a polyvinyl butyralresin was precipitated. Thereafter, the reaction system was kept at 50°C. for 4 hours, and the reaction was finished. The resin was washed withexcess water so that unreacted n-butyl aldehyde was washed away.Further, the hydrochloric acid catalyst was neutralized and the salt wasremoved, and then the product was dried. Thereby, a polyvinyl butyralresin AA was obtained. With respect to the obtained polyvinyl butyralresin AA, the degree of acetylation was 1.0 mol %, the degree ofbutyralization was 62.5 mol %, and the hydroxy group content was 36.5mol %.

Synthesis Example 28 Synthesis of Polyvinyl Butyral Resin AB

A resin AB was obtained by butyralization of polyvinyl alcohol with adegree of saponification of 87.2% and a degree of polymerization of2,300 by a common method. With respect to the obtained polyvinyl butyralresin AB, the degree of acetylation was 12.8 mol %, the degree ofbutyralization was 63.5 mol %, and the hydroxy group content was 23.7mol %.

Synthesis Example 29 Synthesis of Polyvinyl Butyral Resin AC

A resin AC was obtained by butyralization of polyvinyl alcohol with adegree of saponification of 70.5% and a degree of polymerization of2,300 by a common method. With respect to the obtained polyvinyl butyralresin AC, the degree of acetylation was 29.5 mol %, the degree ofbutyralization was 34 mol %, and the hydroxy group content was 36.5 mol%.

Synthesis Example 30 Synthesis of Polyvinyl Butyral Resin AD

A resin AD was obtained by butyralization of polyvinyl alcohol with adegree of saponification of 70.5% and a degree of polymerization of2,300 by a common method. With respect to the obtained polyvinyl butyralresin AD, the degree of acetylation was 29.5 mol %, the degree ofbutyralization was 30.0 mol %, and the hydroxy group content was 40.5mol %.

Example 1 (1) Preparation of Intermediate Film

The obtained polyvinyl butyral resin a (degree of acetylation: 30.5 mol%, 100 parts by weight) and triethylene glycol di-2-ethyl hexanoate (50parts by weight) as a plasticizer were sufficiently kneaded using amixing roll, and thereby a composition for intermediate layer wasobtained.

The polyvinyl butyral resin d (degree of acetylation: 1 mol %, 100 partsby weight) and triethylene glycol di-2-ethyl hexanoate (3GO, 20 parts byweight) as a plasticizer were sufficiently kneaded, and thereby acomposition for protecting layer was obtained.

The obtained composition for intermediate layer and composition forprotecting layer were molded using a co-extruder, and thereby amultilayer intermediate film (thickness: 0.8 mm) having a laminatedstructure of protecting layer B (thickness: 0.35 mm)/intermediate layerA (thickness: 0.1 mm)/protecting layer B (thickness: 0.35 mm) wasprepared.

(2) Preparation of Laminated Glass Used for Measurement of Loss Factor

The obtained multilayer intermediate film was cut into a size of 30 mmin length×320 mm in width. Next, the multilayer intermediate film wassandwiched between two transparent float glasses (25 mm in length×305 mmin width×2.0 mm in thickness). The workpiece was maintained andvacuum-pressed at 90° C. for 30 minutes using a vacuum laminator, andthereby a laminate was obtained. Portions of the multilayer intermediatefilm bulged out of the glasses in the laminate were cut away, andthereby a laminated glass to be used for measurement of loss factor wasobtained.

(3) Preparation of Laminated Glass Used in Bubble Formation Test A andBubble Formation Test B

The obtained multilayer intermediate film was cut into a size of 30 cmin length×15 cm in width, and then stored for 10 hours under the 23° C.condition. Embossment was formed on both surfaces of the obtainedmultilayer intermediate film, and the 10-point average roughness of theembossment was 30 μm. On the cut multilayer intermediate film,6-mm-diameter through holes were formed at four respective points, eachpoint being an intersection of a position that is 8 cm inside from oneedge of the multilayer intermediate film in the length direction and aposition that is 5 cm inside from one edge of the multilayerintermediate film in the width direction.

The multilayer intermediate film with the through holes was sandwichedbetween two transparent float glasses (30 cm in length×15 cm inwidth×2.5 mm in thickness), and thereby a laminate was obtained. Theperipheral edge of the laminate was heat-sealed by 2 cm in width fromthe edge, and thereby the air remained in the embossment and the airremained in the through holes were sealed. This laminate waspress-bonded at 135° C. and 1.2 MPa for 20 minutes, and thereby theresidual air was dissolved into the multilayer intermediate film. As aresult, a laminated glass to be used in the Bubble formation test A andthe Bubble formation test B was obtained. The laminated glass to be usedin the Bubble formation test A and the Bubble formation test B wasprepared using one of the multilayer intermediate films of Examples 6 to41 and Comparative Examples 2 to 4.

Examples 2 to 41 and Comparative Examples 1 to 4

Except that the types and amounts of the polyvinyl butyral resin and thetypes and amounts of the plasticizer used in the intermediate layer Aand the protecting layers B were those shown in Tables 1 to 5, amultilayer intermediate film and a laminated glass were obtained in thesame manner as in Example 1. Further, in Examples 12, 19, and 27, thethickness of the intermediate layer A was 0.13 mm and the thickness ofeach protecting layer B was 0.375 mm. In Examples 13, 20, and 28, thethickness of the intermediate layer A was 0.08 mm and the thickness ofeach protecting layer B was 0.36 mm.

(Evaluation)

(1) Peak Temperature of Tan δ at Low-Temperature Side, Peak MaximumValue of Tan δ at Low-Temperature Side, and Peak Maximum Value of Tan δat High-Temperature Side

The obtained intermediate film was stored in a 20° C. environment forone month, and then the intermediate film was cut out into a8-mm-diameter circular shape. The temperature variance of the dynamicviscoelasticity was measured by a shear method using a rheometer(“ARES”, Rheometric Scientific, Inc.) under the following conditions: astrain of 1.0%, a frequency of 1 Hz, and a temperature-increasing rateof 5° C./min. Thereby, the peak temperature of tan δ at low-temperatureside, the peak maximum value of tan δ at low-temperature side, and thepeak maximum value of tan δ at high-temperature side were measured.

(2) Loss Factor

A Laminated glass to be used for the measurement of loss factor wasstored in a 20° C. environment for one month. The loss factor of thelaminated glass stored in the 20° C. environment for one month wasmeasured by a center exciting method at 20° C. using a measurementdevice “SA-01” (R10N Co., Ltd.). The loss factor (loss factor at 20° C.)in the 4th mode of resonant frequency (around 3,150 Hz) of the lossfactor obtained was evaluated.

Further, the loss factor of the laminated glass stored in the 20° C.environment for one month was measured by a center exciting method at30° C. using a measurement device “SA-01” (R10N Co., Ltd.). The lossfactor (loss factor at 30° C.) in the 6th mode of resonant frequency(around 6,300 Hz) of the loss factor obtained was evaluated.

(3) Bubble Formation Test A (State of Bubble Formation)

With respect to each of the multilayer intermediate films in Examples 6to 41 and Comparative Examples 2 to 4, five laminated glasses to be usedin the bubble formation test A were produced, and then left to stand for100 hours in a 50° C. oven. The left laminated glasses were visuallyobserved for the presence of bubble formation and the size of thebubbles in a plan view, and the state of bubble formation was evaluatedbased on the following criteria.

[Criteria for the State of Bubble Formation in the Bubble Formation TestA]

The bubbles generated in the five laminated glasses each wereapproximated to an ellipse, and the area of the ellipse was defined asthe area of the bubble. The areas of the ellipses observed in the fivelaminated glass were averaged, and the proportion (percentage) of theaveraged value (bubble formation area) of the areas of the ellipses tothe area (30 cm×15 cm) of the laminated glass was determined.

◯◯: No bubble formation was observed in any of five laminated glasses

◯: The ratio of the average value (bubble formation area) of the areasof bubble formation was lower than 5%

Δ: The ratio of the average value (bubble formation area) of the areasof bubble formation was 5% or higher and lower than 10%

x: The ratio of the average value (bubble formation area) of the areasof bubble formation was 10% or higher

(4) Bubble Formation Test B (State of Bubble Formation)

With respect to each of the multilayer intermediate films in Examples 6to 41 and Comparative Examples 2 to 4, 30 laminated glasses to be usedin the bubble formation test B were produced, and then left to stand for24 hours in a 50° C. oven. The number of laminated glasses in whichbubble formation was visually observed among the left laminated glasseswas counted, and the state of bubble formation was evaluated based onthe following criteria.

[Criteria for the State of Bubble Formation in the Bubble Formation TestB]

◯◯: The number of laminated glasses in which bubble formation wasvisually observed was 5 or less

◯: The number of laminated glasses in which bubble formation wasvisually observed was 6 or more and 10 or less

Δ: The number of laminated glasses in which bubble formation wasvisually observed was 11 or more and 15 or less

x: The number of laminated glasses in which bubble formation wasvisually observed was 16 or more

(5) Measurement of Elastic Modulus G′ by Test Method A

The polyvinyl acetal resin to be contained in the intermediate layer(first layer) of the intermediate film for laminated glass of each ofExamples 6 to 41 and Comparative Examples 2 to 4 (the polyvinyl acetalresin used for intermediate layer) (100 parts by weight) and triethyleneglycol di-2-ethyl hexanoate (3GO) (60 parts by weight) as a plasticizerwere sufficiently kneaded, and thereby a kneaded product was obtained.The obtained kneaded product was press-molded using a press-moldingmachine, and thereby a resin film A with an average thickness of 0.35 mmwas obtained. The obtained resin film A was left for two hours at atemperature of 25° C. and a relative humidity of 30%. After two hours,the viscoelasticity was measured using ARES-G2 (TA INSTRUMENTS). Thegeometry used here was a 8-mm-diameter parallel plate. The measurementwas performed under the condition wherein the temperature was loweredfrom 100° C. to −10° C. at a lowering rate of 3° C./min and under thecondition with a frequency of 1 Hz and a strain of 1%. In the obtainedmeasurement results, the peak temperature of the loss factor was definedas a glass transition temperature Tg (° C.). Further, Based on theobtained measurement results and the glass transition temperature Tg,the value of the elastic modulus G′(Tg+30) at (Tg+30)° C. and the valueof the elastic modulus G′(Tg+80) at (Tg+80)° C. were read, and the ratio(G′(Tg+80)/G′(Tg+30)) was determined.

(6) Measurement of Elastic Modulus G′ by Test Method B

The intermediate film for laminated glass of each of Examples 6 to 41and Comparative Examples 2 to 4 was stored in a constant temperature andhumidity facility (humidity: 30% (±3%), temperature: 23° C.) for onemonth. Immediately after the storage for one month, the surface layer,the intermediate layer, and the surface layer were separated, andthereby the intermediate layer was taken out. One gram of the separatedintermediate layer was placed in a mold (2 cm in length×2 cm inwidth×0.76 mm in thickness) disposed between two polyethyleneterephthalate (PET) films. The intermediate layer was preheated at atemperature of 150° C. and a pressure of 0 kg/cm² for 10 minutes, andthen press-molded at 80 kg/cm² for 15 minutes. The press-moldedintermediate layer was placed in a hand press set to 20° C. in advance,and then pressed at 10 MPa for 10 minutes. Thereby, the intermediatelayer was cooled down. Next, one of the two PET films was peeled offfrom the mold disposed therebetween, and it was stored in a constanttemperature and humidity facility (humidity: 30% (±3%), temperature: 23°C.) for 24 hours. Then, the viscoelasticity was measured using ARES-G2(TA INSTRUMENTS). The geometry used here was a 8-mm-diameter parallelplate. The measurement was performed under the condition wherein thetemperature was lowered from 100° C. to −10° C. at a lowering rate of 3°C./rain and under the condition with a frequency of 1 Hz and a strain of1%. In the obtained measurement results, the peak temperature of theloss factor was defined as a glass transition temperature Tg (° C.).Further, based on the obtained measurement results and the glasstransition temperature Tg, the value of the elastic modulus G′(Tg+30) at(Tg+30)° C. and the value of the elastic modulus G′(Tg+80) at (Tg+80)°C. were read. In addition, the ratio (G′(Tg+80)/G′(Tg+30)) wasdetermined.

(7) Measurement of Absolute Molecular Weight and Molecular Weight y(Measurement of Absolute Molecular Weight)

The absolute molecular weight and the molecular weight in terms ofpolystyrene for determining the ratio of the high-molecular-weightcomponent X and the high-molecular-weight component Y mentioned inSynthesis Example 8 were values determined by separating the surfacelayers and the intermediate layer of the obtained multilayerintermediate film, and then performing the following steps.

In order to measure the absolute molecular weight, the multilayerintermediate film was left in a constant temperature and humidityfacility (humidity: 30% (±3%), temperature: 23° C.) for one month. Afterone month, the surface layers and the intermediate layer of theintermediate film were separated. The separated intermediate layer wasdissolved in tetrahydrofuran (THF) to prepare a 0.1 wt % solution. Theobtained solution was analyzed using a Gel Permeation Chromatography(GPC) device (Hitachi High-Technologies Corp., RI: L2490, auto-sampler:L-2200, pump: L-2130, column oven: L-2350, columns: GL-A120-S andGL-A100MX-S in series). This GPC device was connected with a lightscattering detector for GPC (VISCOTEK, Model 270 (RALS+VISCO)), and thusthe chromatograms of the respective detectors can be analyzed. The peaksof the polyvinyl acetal resin component in the chromatograms of the RIdetector and RALS detector were analyzed using an analysis software(OmniSEC), and thereby the absolute molecular weight at each elutiontime of the polyvinyl acetal resin was determined. The ratio of the areaof a region where the absolute molecular weight of the polyvinyl acetalresin is 1,000,000 or higher in the peak area of the polyvinyl acetalresin detected by the RI detector was represented in percentage (%).

The following formulas hold for the peaks of the respective componentsin the chromatograms.

A _(RI) =c×(dn/dc)×K _(RI)  (1)

A _(RALS) =c×M×(dn/dc)² ×K _(RALS)  (2)

In the formulas, c represents the polymer concentration in solution,(dn/dc) represents the increment of refractive index, M represents theabsolute molecular weight, and K represents the system's coefficient.

In the specific measurement procedure, first, 0.1 wt % THF solution wasprepared using a polystyrene standard sample (VISCOTEK Corp., PolyCAL(registered trademark) TDS-PS-NB, Mw=98,390, do/dc=0.185) with known c,M, and (dn/dc) values. Based on the GPC measurement result of theobtained polystyrene solution, the system's coefficient K of eachdetector was determined using the formula (1) and the formula (2).

Next, the separated intermediate layer was dissolved in THF, and therebya THF solution was prepared. Based on the GPC measurement result of theobtained polyvinyl acetal resin solution, the absolute molecular weightM of the polyvinyl acetal resin was determined using the formula (1) andthe formula (2).

Here, in order to analyze the intermediate layer (containing polyvinylacetal resin and plasticizer), the concentration of the polyvinyl acetalresin in the polyvinyl acetal resin solution needs to be determined. Theconcentration of the polyvinyl acetal resin was calculated from resultof the following measurement of amount of plasticizer.

Measurement of Amount of Plasticizer:

The plasticizer was dissolved in THF such that the amount of theplasticizer was to be 10% by weight, 15% by weight, 20% by weight, 25%by weight, 30% by weight, 35% by weight, 40% by weight, 45% by weight,or 50% by weight, and thereby a plasticizer-THF solution was prepared.The obtained plasticizer-THF solution was subjected to GPC measurement,and the peak area of the plasticizer was determined. The peak areas ofthe plasticizer were plotted with respect to each concentration of theplasticizer, and thereby an approximate straight line was obtained.Next, the THF solution containing the intermediate layer dissolved inTHF was subjected to GPC measurement, and the amount of the plasticizerwas determined from the peak area of the plasticizer using theapproximate straight line.

(Measurement of Molecular Weight y)

In the same manner as in the aforementioned measurement method of theabsolute molecular weight, the molecular weight in terms of polystyrenewas measured by gel permeation chromatography (GPC). The proportion (%)of the high-molecular-weight component Y with a molecular weight y of1,000,000 or higher in the polyvinyl acetal resin was calculated fromthe ratio of the area corresponding to a region where the molecularweight was 1,000,000 or higher among the peak areas detected by the RIdetector (measurement results of GPC).

In order to measure the molecular weight in terms of polystyrene, thepolystyrene standard samples with known molecular weights were subjectedto GPC measurement. As the polystyrene standard samples (“ShodexStandard SM-105”, “Shodex Standard SH-75”, SHOWA DENKO K.K.) were used14 samples with the respective weight average molecular weights of 580,1,260, 2,960, 5,000, 10,100, 21,000, 28,500, 76,600, 196,000, 630,000,1,130,000, 2,190,000, 3,150,000, and 3,900,000. Weight average molecularweights were plotted with respect to the corresponding elution timesindicated by the peak tops of the peaks of the respective standardsamples, and the obtained approximate straight line was used as acalibration curve. A multilayer intermediate film was left in a constanttemperature and humidity facility (humidity: 30% (±3%), temperature: 23°C.) for one month, and then the surface layers and the intermediatelayer were separated. The separated intermediate layer was dissolved intetrahydrofuran (THF) to prepare a 0.1 wt % solution. The obtainedsolution was analyzed using a GPC device, and the peak area of thepolyvinyl acetal resin in the intermediate layer was measured. Next, thearea corresponding to the region where the molecular weight in terms ofpolystyrene of the polyvinyl acetal resin in the intermediate layer was1,000,000 or higher was calculated from the elution time and thecalibration curve of the polyvinyl acetal resin in the intermediatelayer. The proportion (%) of the high-molecular-weight component Y witha molecular weight y of 1,000,000 or higher in the polyvinyl acetalresin was calculated by representing in percentage (%) the valueobtained by dividing the area corresponding to the region where themolecular weight in terms of polystyrene of the polyvinyl acetal resinin the intermediate layer was 1,000,000 or higher by the peak area ofthe polyvinyl acetal resin in the intermediate layer.

The results are shown in the following Tables 1 to 5. In the followingTables 1 to 5, “3GO” represents triethylene glycol di-2-ethyl hexanoate,“DBA” represents dibutyl adipate, and “3 GB” represents triethyleneglycol dibutyrate.

TABLE 1 Example Example Example Example Example Comparative 1 2 3 4 5Example 1 Inter- Resin Type a b c f g e mediate Degree of 40 35 25 59 4563.5 layer A butyralization (mol %) Degree of 30.5 40 50 35 40 12.8acetylation (mol %) Amount (parts 100 100 100 100 100 100 by weight)Plasti- Type 3GO 3GO 3GO 3GO 3GO 3GO cizer Amount (parts 50 45 40 40 4060 by weight) Protecting Resin Type d d d d d d layer B Degree of 68.568.5 68.5 68.5 68.5 68.5 butyralization (mol %) Degree of 1 1 1 1 1 1acetylation (mol %) Amount (parts 100 100 100 100 100 100 by weight)Plasti- Type 3GO 3GO 3GO 3GO 3GO 3GO cizer Amount (parts 20 20 20 38.538.5 38.5 by weight) Layer structure B/A/B B/A/B B/A/B B/A/B B/A/B B/A/BPeak temperature of tan δ at low- −2.4 −3.2 −4 −2.8 −3.6 −1.8temperature side Peak maximum value of tan δ at low- 1.38 1.46 1.51 1.581.64 1.05 temperature side Peak maximum value of tan δ at high- 0.560.59 0.55 0.52 0.51 0.54 temperature side Loss factor at 20° C. around3,150 Hz 0.31 0.33 0.36 0.49 0.5 0.28 Loss factor at 30° C. around 6,300Hz 0.12 0.14 0.16 0.17 0.18 0.09

TABLE 2 Example Example Example Example Example Example 6 7 8 9 10 11Inter- Resin Type h i j k l m mediate Degree of 58 26 13 58 52 50 layerA butyralization (mol %) Degree of 35 67 80 40 32 30.5 acetylation (mol%) Amount (parts 100 100 100 100 100 100 by weight) Plasti- Type 3GO 3GO3GO 3GO 3GO 3GO cizer Amount (parts 50 50 50 50 50 50 by weight)Protecting Resin Type d d d d d d layer B Degree of 68.5 68.5 68.5 68.568.5 68.5 butyralization (mol %) Degree of 1 1 1 1 1 1 acetylation (mol%) Amount (parts 100 100 100 100 100 100 by weight) Plasti- Type 3GO 3GO3GO 3GO 3GO 3GO cizer Amount (parts 28 30 34 27 30 33 by weight)) Layerstructure B/A/B B/A/B B/A/B B/A/B B/A/B B/A/B Peak temperature of tan δat low- −1.7 −2.2 −2.7 −3.1 −2.9 −3.52 temperature side (° C.) Peakmaximum value of tan δ at low- 1.66 1.64 1.59 1.74 1.58 1.57 temperatureside Peak maximum value of tan δ at high- 0.55 0.56 0.55 0.56 0.56 0.55temperature side Loss factor at 20° C. around 3,150 Hz 0.53 0.52 0.510.56 0.49 0.49 Loss factor at 30° C. around 6,300 Hz 0.18 0.17 0.17 0.20.15 0.16 Bubble formation test A (state of Bubble ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘formation) Bubble formation test B (state of Bubble ∘ ∘ ∘ ∘ ∘ ∘formation) Test method A: glass transition −2.51 −2.9 −3.2 −3.7 −3.5−2.88 temperature (Tg) (° C.) Test method A: G′ (Tg + 30) (Pa) 231500223000 219000 212000 214500 234000 Test method A: G′ (Tg + 80) (Pa)158000 154600 149800 143000 145000 159000 Test method A: G′ (Tg + 80)/G′0.68 0.59 0.68 0.67 0.66 0.68 (Tg + 30) Test method B: glass transition−4.72 −4.22 −6.2 −5.8 −5.41 −4.12 temperature (Tg) (° C.) Test method B:G′ (Tg + 30) (Pa) 221500 216900 198500 201500 204300 225600 Test methodB: G′ (Tg + 80) (Pa) 150400 148300 132700 132500 135400 152700 Testmethod B: G′ (Tg + 80)/G′ 0.68 0.68 0.67 0.66 0.66 0.68 (Tg + 30)Proportion of high-molecular-weight 19.6 — — — — — component X (%)Proportion of high-molecular-weight 23.1 — — — — — component Y (%)Example Example Example Example Example 12 13 14 15 16 Inter- Resin Typen n n n n mediate Degree of 55 55 55 55 55 layer A butyralization (mol%) Degree of 30.5 30.5 30.5 30.5 30.5 acetylation (mol %) Amount (parts100 100 100 100 100 by weight) Plasti- Type 3GO 3GO 3GO 3GO 3GO cizerAmount (parts 50 50 50 50 50 by weight) Protecting Resin Type d d o p dlayer B Degree of 68.5 68.5 68.5 72.4 68.5 butyralization (mol %) Degreeof 1 1 1.8 1.2 1 acetylation (mol %) Amount (parts 100 100 100 100 100by weight) Plasti- Type 3GO 3GO 3GO 3GO 3GO cizer Amount (parts 31 31 3536 32.5 by weight)) Layer structure B/A/B B/A/B B/A/B B/A/B B/A/B Peaktemperature of tan δ at low- −4.12 −4.21 −4.88 −5.12 −4.65 temperatureside (° C.) Peak maximum value of tan δ at low- 1.74 1.62 1.64 1.62 1.67temperature side Peak maximum value of tan δ at high- 0.51 0.53 0.560.58 0.54 temperature side Loss factor at 20° C. around 3,150 Hz 0.550.5 0.51 0.5 0.52 Loss factor at 30° C. around 6,300 Hz 0.19 0.17 0.170.16 0.17 Bubble formation test A (state of Bubble ∘∘ ∘∘ ∘∘ ∘∘ ∘∘formation) Bubble formation test B (state of Bubble ∘ ∘ ∘ ∘ ∘ formation)Test method A: glass transition −4.67 −4.67 −4.67 −4.67 −4.67temperature (Tg) (° C.) Test method A: G′ (Tg + 30) (Pa) 228500 228500228500 228500 228500 Test method A: G′ (Tg + 80) (Pa) 157900 157900157900 157900 157900 Test method A: G′ (Tg + 80)/G′ 0.69 0.69 0.69 0.690.69 (Tg + 30) Test method B: glass transition −4.53 −4.6 −5.12 −5.33−5.02 temperature (Tg) (° C.) Test method B: G′ (Tg + 30) (Pa) 227500227000 221300 220700 224300 Test method B: G′ (Tg + 80) (Pa) 154300156000 152800 150600 154200 Test method B: G′ (Tg + 80)/G′ 0.68 0.690.69 0.68 0.69 (Tg + 30) Proportion of high-molecular-weight — — — — —component X (%) Proportion of high-molecular-weight — — — — — componentY (%)

TABLE 3 Example Example Example Example Example Example 17 18 19 20 2122 Inter- Resin Type q r r r r r mediate Degree of 65 45 45 45 45 45layer A butyralization (mol %) Degree of 30.5 40 40 40 40 40 acetylation(mol %) Amount (parts 100 100 100 100 100 100 by weight) Plasti- Type3GO 3GO 3GO 3GO 3GO 3GO cizer Amount (parts 50 50 50 50 50 50 by weight)Protecting Resin Type d d d d o p layer B Degree of 68.5 68.5 68.5 68.568.5 72.4 butyralization (mol %) Degree of 1 1 1 1 1.8 1.2 acetylation(mol %) Amount (parts 100 100 100 100 100 100 by weight) Plasti- Type3GO 3GO 3GO 3GO 3GO 3GO cizer Amount (parts 34 28 28 28 32 34 by weight)Layer structure B/A/B B/A/B B/A/B B/A/B B/A/B B/A/B Peak temperature oftan δ at low- −3.77 −4.12 −4.65 −5.01 −4.22 −4.56 temperature side (°C.) Peak maximum value of tan δ at low- 1.75 1.69 1.76 1.63 1.67 1.65temperature side Peak maximum value of tan δ at high- 0.54 0.53 0.5 0.510.54 0.55 temperature side Loss factor at 20° C. around 3,150 Hz 0.560.52 0.55 0.5 0.51 0.51 Loss factor at 30° C. around 6,300 Hz 0.2 0.170.2 0.16 0.16 0.16 Bubble formation test A (state of Bubble ∘∘ ∘∘ ∘∘ ∘∘∘∘ ∘∘ formation) Bubble formation test B (state of Bubble ∘ ∘ ∘ ∘ ∘ ∘formation) Test method A: glass transition −6.43 −8.21 −8.21 −8.21 −8.21−8.21 temperature(Tg) (° C.) Test method A: G′ (Tg + 30) (Pa) 202700210600 210600 210600 210600 210600 Test method A: G′ (Tg + 80) (Pa)136000 145700 145700 145700 145700 145700 Test method A: G′ (Tg + 80)/G′0.67 0.69 0.69 0.69 0.69 0.69 (Tg + 30) Teat method B: glass transition−4.11 −4.56 −4.83 −5.33 −4.56 −5.02 temperature(Tg) (° C.) Test methodB: G′ (Tg + 30) (Pa) 219600 224600 226000 221500 225300 224600 Testmethod B: G′ (Tg + 80) (Pa) 145800 152400 153200 153700 153000 153200Test method B: G′ (Tg + 80)/G′ 0.66 0.68 0.68 0.69 0.68 0.68 (Tg + 30)Proportion of high-molecular-weight — — — — — — component X (%)Proportion of high-molecular-weight — — — — — — component Y (%) ExampleExample Example Example Example 23 24 25 26 27 Inter- Resin Type r t u vv mediate Degree of 45 50 45 33.5 33.5 layer A butyralization (mol %)Degree of 40 40 50.7 50.2 50.2 acetylation (mol %) Amount (parts 100 100100 100 100 by weight) Plasti- Type 3GO 3GO 3GO 3GO 3GO cizer Amount(parts 50 50 50 50 50 by weight) Protecting Resin Type s d d d d layer BDegree of 62.5 68.5 68.5 68.5 68.5 butyralization (mol %) Degree of 1 11 1 1 acetylation (mol %) Amount (parts 100 100 100 100 100 by weight)Plasti- Type 3GO 3GO 3GO 3GO 3GO cizer Amount (parts 24 30 34 31 31 byweight) Layer structure B/A/B B/A/B B/A/B B/A/B B/A/B Peak temperatureof tan δ at low- −4.33 −3.54 −4.77 −4.21 −4.51 temperature side (° C.)Peak maximum value of tan δ at low- 1.74 1.74 1.78 1.72 1.76 temperatureside Peak maximum value of tan δ at high- 0.55 0.56 0.52 0.54 0.57temperature side Loss factor at 20° C. around 3,150 Hz 0.55 0.56 0.570.55 0.56 Loss factor at 30° C. around 6,300 Hz 0.19 0.2 0.21 0.19 0.2Bubble formation test A (state of Bubble ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ formation)Bubble formation test B (state of Bubble ∘ ∘ ∘ ∘ ∘ formation) Testmethod A: glass transition −12.14 −5.77 −3.12 −5.68 −5.68temperature(Tg) (° C.) Test method A: G′ (Tg + 30) (Pa) 200400 205300229200 224500 224500 Test method A: G′ (Tg + 80) (Pa) 134500 136900152900 153900 153900 Test method A: G′ (Tg + 80)/G′ 0.67 0.67 0.67 0.690.69 (Tg + 30) Teat method B: glass transition −4.83 −4.1 −5.04 −4.51−4.86 temperature(Tg) (° C.) Test method B: G′ (Tg + 30) (Pa) 225600220100 206400 227400 226000 Test method B: G′ (Tg + 80) (Pa) 149700148000 135900 156100 155800 Test method B: G′ (Tg + 80)/G′ 0.66 0.670.66 0.69 0.69 (Tg + 30) Proportion of high-molecular-weight — — — — —component X (%) Proportion of high-molecular-weight — — — — — componentY (%)

TABLE 4 Example Example Example Example Example Example 28 29 30 31 3233 Inter- Resin Type v v v w x y mediate Degree of 33.5 33.5 33.5 28.435 29.5 layer A butyralization (mol %) Degree of 50.2 50.2 50.2 50.5 6060 acetylation (mol %) Amount (parts 100 100 100 100 100 100 by weight)Plasti- Type 3GO 3GO 3GO 3GO 3GO 3GO cizer Amount (parts 50 50 50 50 5050 by weight) Protecting Resin Type d o p d d d layer B Degree of 68.568.5 72.4 68.5 68.5 68.5 butyralization (mol %) Degree of 1 1.8 1.2 1 11 acetylation (mol %) Amount (parts 100 100 100 100 100 100 by weight)Plasti- Type 3GO 3GO 3GO 3GO 3GO 3GO cizer Amount (parts 31 34 36 33 3533 by weight) Layer structure B/A/B B/A/B B/A/B B/A/B B/A/B B/A/B Peaktemperature of tan δ at low- −4.77 −4.66 −5.24 −4.56 −3.88 −4.01temperature side (° C.) Peak maximum value of tan δ at low- 1.66 1.71.68 1.61 1.74 1.73 temperature side Peak maximum value of tan δ athigh- 0.54 0.56 0.58 0.55 0.54 0.55 temperature side Loss factor at 20°C. around 3,150 Hz 0.51 0.52 0.52 0.5 0.55 0.54 Loss factor at 30° C.around 6,300 Hz 0.18 0.18 0.18 0.17 0.2 0.2 Bubble formation test A(state of Bubble ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ formation) Bubble formation test B(state of Bubble ∘ ∘ ∘ ∘ ∘ ∘ formation) Test method A: glass transition−5.68 −5.68 −5.68 −3.84 −2.52 −3.86 temperature (Tg) (° C.) Test methodA: G′ (Tg + 30) (Pa) 224500 224500 224300 228400 231800 229800 Testmethod A: G′ (Tg + 80) (Pa) 153900 153900 153900 161000 154600 156000Test method A: G′ (Tg + 80)/G′ 0.69 0.69 0.69 0.70 0.67 0.68 (Tg + 30)Test method B: glass transition −5.22 −5.05 −5.64 −5.37 −4.11 −4.5temperature (Tg) (° C.) Test method B: G′ (Tg + 30) (Pa) 224700 218000209300 210400 213800 220500 Test method B: G′ (Tg + 80) (Pa) 156000150800 143600 147600 140700 146800 Test method B: G′ (Tg + 80)/G′ 0.690.69 0.69 0.70 0.66 0.67 (Tg + 30) Proportion of high-molecular-weight —— — — — — component X (%) Proportion of high-molecular-weight — — — — —— component Y (%) Example Example Example Example Example 34 35 36 37 38Inter- Resin Type y y y y z mediate Degree of 29.5 29.5 29.5 29.5 24.3layer A butyralization (mol %) Degree of 60 60 60 60 60 acetylation (mol%) Amount (parts 100 100 100 100 100 by weight) Plasti- Type 3GO 3GO 3GO3GO 3GO cizer Amount (parts 50 50 50 50 50 by weight) Protecting ResinType d d o p d layer B Degree of 68.5 68.5 68.5 72.4 68.5 butyralization(mol %) Degree of 1 1 1.8 1.2 1 acetylation (mol %) Amount (parts 100100 100 100 100 by weight) Plasti- Type 3GO 3GO 3GO 3GO 3GO cizer Amount(parts 33 33 36 37.5 35 by weight) Layer structure B/A/B B/A/B B/A/BB/A/B B/A/B Peak temperature of tan δ at low- −4.23 −4.56 −4.22 −5.02−4.65 temperature side (° C.) Peak maximum value of tan δ at low- 1.751.63 1.7 1.68 1.61 temperature side Peak maximum value of tan δ at high-0.51 0.53 0.57 0.58 0.57 temperature side Loss factor at 20° C. around3,150 Hz 0.56 0.5 0.52 0.51 0.49 Loss factor at 30° C. around 6,300 Hz0.2 0.18 0.18 0.18 0.17 Bubble formation test A (state of Bubble ∘∘ ∘∘∘∘ ∘∘ ∘∘ formation) Bubble formation test B (state of Bubble ∘ ∘ ∘ ∘ ∘formation) Test method A: glass transition −3.86 −3.86 −3.86 −3.86 −4.29temperature (Tg) (° C.) Test method A: G′ (Tg + 30) (Pa) 229800 229800229800 229800 227700 Test method A: G′ (Tg + 80) (Pa) 156000 156000156000 156000 160400 Test method A: G′ (Tg + 80)/G′ 0.68 0.68 0.68 0.680.70 (Tg + 30) Test method B: glass transition −4.52 −4.88 −4.56 −5.49−4.87 temperature (Tg) (° C.) Test method B: G′ (Tg + 30) (Pa) 220700222200 218900 208100 223700 Test method B: G′ (Tg + 80) (Pa) 147100147900 148800 140600 157200 Test method B: G′ (Tg + 80)/G′ 0.67 0.670.68 0.68 0.70 (Tg + 30) Proportion of high-molecular-weight — — — — —component X (%) Proportion of high-molecular-weight — — — — — componentY (%)

TABLE 5 Example Example Example Comparative Comparative Comparative 3940 41 Example 2 Example 3 Example 4 Inter- Resin Type r r r AB AC ADmediate Degree of 45 45 45 63.5 34 30 layer A butyralization (mol %)Degree of 40 40 40 12.8 29.5 29.5 acetylation (mol %) Amount (parts 100100 100 100 100 100 by weight) Kind of plasticizer 3GB DBA 3GH 3GO 3GO3GO Amount of plasticizer 40 40 50 60 60 60 (parts by weight) ProtectingResin Type AA AA d d d d layer B Degree of 62.5 62.5 68.5 68.5 68.5 68.5butyralization (mol %) Degree of 1 1 1 1 1 1 acetylation (mol %) Amount(parts 100 100 100 100 100 100 by weight) Kind of plasticizer 3GB DBA3GH 3GO 3GO 3GO Amount of plasticizer 30 30 26.5 37.5 37.5 37.5 (partsby weight) Layer structure B/A/B B/A/B B/A/B B/A/B B/A/B B/A/B Peaktemperature of tan δ at low- −4.27 −4.02 −3.24 −2.43 −2.85 4.22temperature side (° C.) Peak maximum value of tan δ at low- 1.82 1.751.73 1.03 1.05 1.07 temperature side Peak maximum value of tan δ athigh- 0.56 0.55 0.55 0.53 0.53 0.53 temperature side Loss factor at 20°C. around 3,150 Hz 0.55 0.54 0.53 0.28 0.29 0.22 Loss factor at 30° C.around 6,300 Hz 0.19 0.18 0.18 0.09 0.09 0.14 Bubble formation test A(state of Bubble ∘∘ ∘∘ ∘∘ x x x formation) Bubble formation test B(state of Bubble ∘ ∘ ∘ x x x formation) Test method A: glass transition−12.56 −11.88 −10.45 1.8 1.99 7.21 temperature (Tg) (° C.) Test methodA: G′ (Tg + 30) (Pa) 184500 187500 211600 236500 237700 265000 Testmethod A: G′ (Tg + 80) (Pa) 123900 128400 143700 142000 143500 163500Test method A: G′ (Tg + 80)/G′ 0.67 0.68 0.68 0.60 0.60 0.62 (Tg + 30)Test method B: glass transition −5.01 −4.76 −4.14 −3.2 −3.33 3.77temperature (Tg) (° C.) Test method B: G′ (Tg + 30) (Pa) 224700 225600229300 226000 227300 245700 Test method B: G′ (Tg + 80) (Pa) 150000150800 153600 131000 132500 146500 Test method B: G′ (Tg + 80)/G′ 0.670.67 0.67 0.58 0.58 0.60 (Tg + 30) Proportion of high-molecular-weight —— — — — — component X (%) Proportion of high-molecular-weight — — — — —— component Y (%)

As shown in Tables 2 to 5, in the intermediate films for laminated glassin the examples and comparative examples, as the result of using theresin film B (first layer) containing the polyvinyl acetal resinconstituting the first layer and the plasticizer constituting the firstlayer in amounts shown in Tables 2 to 5 and allowing the plasticizers totransfer between the respective layers of the multilayer intermediatefilm, and then measuring the elastic modulus G′ of the resin film B(first layer), the ratio (G′(Tg+80)/G′(Tg+30)) of the resin film B wassubstantially the same as the ratio (G′(Tg+80)/G′(Tg+30)) of the resinfilm A containing 100 parts by weight of the polyvinyl acetal resin and60 parts by weight of the 3GO contained in the first layer.

EXPLANATION OF SYMBOLS

-   -   1: intermediate film    -   1 a: first surface    -   1 b: second surface    -   2: first layer    -   2 a: first surface    -   2 b: second surface    -   3: second layer    -   3 a: outer surface    -   4: third layer    -   4 a: outer surface    -   11: laminated glass    -   21: first component for laminated glass    -   22: second component for laminated glass

1. An intermediate film for laminated glass with a single layerstructure or a laminated structure of two or more layers, comprising: afirst layer containing a polyvinyl acetal resin and a plasticizer,wherein a degree of acetylation of the polyvinyl acetal resin containedin the first layer exceeds 30 mol %.
 2. The intermediate film forlaminated glass with a laminated structure of two or more layersaccording to claim 1, further comprising a second layer disposed at theside of a first surface of the first layer.
 3. The intermediate film forlaminated glass according to claim 2, wherein the second layer containsa polyvinyl acetal resin, and a degree of acetylation of the polyvinylacetal resin contained in the second layer is lower than the degree ofacetylation of the polyvinyl acetal resin contained in the first layer.4. The intermediate film for laminated glass according to claim 3,wherein the degree of acetylation of the polyvinyl acetal resincontained in the second layer is 30 mol % or lower.
 5. The intermediatefilm for laminated glass according to claim 2, wherein the second layercontains the polyvinyl acetal resin and a plasticizer, and an amount ofthe plasticizer for each 100 parts by weight of the polyvinyl acetalresin in the second layer is less than an amount of the plasticizer foreach 100 parts by weight of the polyvinyl acetal resin in the firstlayer.
 6. The intermediate film for laminated glass according to claim2, wherein the second layer is laminated on the first surface of thefirst layer.
 7. The intermediate film for laminated glass with alaminated structure of two or more layers according to claim 1, furthercomprising a second layer which is laminated on a first surface of thefirst layer and which contains a polyvinyl acetal resin and aplasticizer, wherein an amount of the plasticizer is 50 parts by weightor more for each 100 parts by weight of the polyvinyl acetal resin inthe first layer, a hydroxy group content in the polyvinyl acetal resincontained in the first layer is lower than a hydroxy group content inthe polyvinyl acetal resin contained in the second layer, the differencebetween the hydroxy group content in the polyvinyl acetal resincontained in the first layer and the hydroxy group content in thepolyvinyl acetal resin contained in the second layer is 9.2 or smaller,and the degree of acetylation of the polyvinyl acetal resin contained inthe first layer is 8 mol % or lower if the difference between thehydroxy group content in the polyvinyl acetal resin contained in thefirst layer and the hydroxy group content in the polyvinyl acetal resincontained in the second layer is greater than 8.5 mol % but not greaterthan 92 mol %.
 8. The intermediate for laminated glass according toclaim 1, wherein the polyvinyl acetal resin contained in the first layercontains a high-molecular-weight component with an absolute molecularweight of 1,000,000 or higher and a proportion of thehigh-molecular-weight component in the polyvinyl acetal resin containedin the first layer is 7.4% or higher, or the polyvinyl acetal resincontained in the first layer contains a high-molecular-weight componentwith a molecular weight in terms of polystyrene of 1,000,000 or higherand a proportion of the high-molecular-weight component in the polyvinylacetal resin contained in the first layer is 9% or higher.
 9. Theintermediate for laminated glass according to claim 1, wherein a ratio(G′(Tg+80)/G′(Tg+30)) of an elastic modulus G′(Tg+80) at (Tg+80)° C. toan elastic modulus G′(Tg+30) at (Tg+30)° C. is 0.65 or higher, providedthat the first layer is used as a resin film and a viscoelasticity ofthe resin film is measured, and that Tg (° C.) represents a glasstransition temperature of the resin film.
 10. The intermediate film forlaminated glass according to claim 1, wherein a ratio(G′(Tg+80)/G′(Tg+30)) of an elastic modulus G′(Tg+80) at (Tg+80)° C. toan elastic modulus G′(Tg+30) at (Tg+30)° C. is 0.65 or higher, providedthat a resin film containing 100 parts by weight of the polyvinyl acetalresin contained in the first layer and 60 parts by weight of triethyleneglycol di-2-ethyl hexanoate (3GO) as a plasticizer is prepared and aviscoelasticity of the resin film is measured, and that Tg (SC)represents a glass transition temperature of the resin film.
 11. Theintermediate film for laminated glass according to claim 1, wherein thepolyvinyl acetal resin contained in the first layer is obtained byacetalizing a polyvinyl alcohol resin having an average degree ofpolymerization exceeding 3,000.
 12. The intermediate film for laminatedglass with a laminated structure of three or more layers according toclaim 1, further comprising: a second layer disposed at the side of afirst surface of the first layer; and a third layer disposed at the sideof a second surface that is opposite to the first surface of the firstlayer.
 13. The intermediate film for laminated glass according to claim12, wherein the third layer contains a polyvinyl acetal resin, and adegree of acetylation of the polyvinyl acetal resin contained in thethird layer is lower than a degree of acetylation of the polyvinylacetal resin contained in the first layer.
 14. The intermediate film forlaminated glass according to claim 13, wherein the degree of acetylationof the polyvinyl acetal resin contained in the third layer is 30 mol %or lower.
 15. The intermediate film for laminated glass according, toclaim 12, wherein the third layer contains a polyvinyl acetal resin anda plasticizer, and an amount of the plasticizer for each 100 parts byweight of the polyvinyl acetal resin in the third layer is lower than anamount of the plasticizer for each 100 parts by weight of the polyvinylacetal resin in the first layer.
 16. The intermediate film for laminatedglass according to claim 12, wherein the third layer is laminated on thesecond surface of the first layer.
 17. A laminated glass, comprising: afirst component for laminated glass; a second component for laminatedglass; and an intermediate film sandwiched between the first componentfor laminated glass and the second component for laminated glass,wherein the intermediate film is the intermediate film for laminatedglass according to claim 1.